20210531, 01:05  #12 
"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
3563_{10} Posts 
Suggest lower case letters for variables, upper case letters for these functions: (remove: "!!" = double factorial and "##" = product of first n primes)
Code:
A n!  (n1)! + (n2)!  ... 1! A005165 B Bell numbers A000110 C Catalan numbers A000108 D Distinct partition numbers A000009 E Euler zigzag numbers A000111 F Fermat numbers A000215 G Fubini numbers A000670 H H(m,n) = nth mFibonacci numbers A000045 A000129 A006190 A001076 ... I I(m,n) = nth mstep Fibonacci numbers A000045 A000073 A000078 A001591 ... J Coefficients of modular function j as power series in q = e^(2 Pi i t) A000521 K 1! + 2! + 3! + ... + n! A007489 L L(m,n) = nth mLucas numbers A000032 A002203 A006497 A014448 ... M Mersenne numbers A000225 N N(m,n) = n!_(m) = mfactorial of n O O(m,n) = mth cyclotomic polynomial evaluated at n P Partition numbers A000041 Q Perrin numbers A001608 R R(m,n) = repunit in base m with length n S S(m,n) = (Smarandache numbers) the concatenate the first n integers in base m T Ramanujan's tau function A000594 U U(n,p,q) = Lucas sequence U_n(p,q) V V(n,p,q) = Lucas sequence V_n(p,q) W W(m,n) = (Wolstenholme numbers) numerator of 1 + 1/(2^m) + 1/(3^m) + ... + 1/(n^m) X X(m,n) = (SmarandacheWellin numbers) the concatenate the first n primes in base m Y Y(m,n) = nth mstep Lucas numbers A000032 A001644 A073817 A074048 ... Z Motzkin numbers A001006 ! Factorial # Primorial % Modulo operator \ Integer division @ n@ = nth prime & Narayana's cows sequence A000930 $ Padovan sequence A000931 : :(m,n,r,s,...) = LCM(m,n,r,s,...) (least common multiple) ; ;(m,n,r,s,...) = GCD(m,n,r,s,...) (greatest common divisor) ~ ~(abc(de)^(fg)hij,n) = string "abcdedede...dededehij" (with fg de's, this fg is written in base 10) in base n (n must be >=2 and <=36) (the letters in the m of ~(m,n) must be upper case, and the m does not support any functions include +*/, and if there are any variable in m, the variable is read in base n (except when the variable is in fg, in this case, the variable is still read in base 10)) Last fiddled with by sweety439 on 20210531 at 02:01 
20210608, 15:39  #13 
"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
7×509 Posts 
the sequence in factordb can add the problem in https://oeis.org/A195264 and https://oeis.org/A316941 (like the home prime problem https://oeis.org/A037274), also the sequences in http://www.aliquotes.com/autres_proc...iteratifs.html (n > sigma(n)n+k for fixed constant k>=1) (the original Aliquot sequence is n > sigma(n)n, i.e. k=0) (the k=1 case can be called "quasiAliquot sequence", like "quasiperfect number" is n=sigma(n)n1 and "quasiamicable pair" is betrothed pair, such as 48 and 75; also the k=1 case can be called "almost Aliquot sequence", like "almost perfect number" is n=sigma(n)n+1)
Also, the home prime problem and inverse home prime problem can include all bases 2<=b<=36 Also I think that the sequence "Greatest prime factor ^2+1" is silly, as the sequences never terminate at a prime unless the start number is power of 2, also "Greatest prime factor ^21", "Greatest prime factor ^3+1", etc. Last fiddled with by sweety439 on 20210608 at 15:48 
20210610, 17:42  #14 
"Daniel Jackson"
May 2011
14285714285714285714
2^{2}×3×59 Posts 
I use those "Greatest Prime Factor" sequences (mostly GPF^3+1 and GPF^31, but I've also run the q^21 sequences of all factored RSA numbers) to see if they ever end in a cycle, so we can't get rid of those.

20210623, 00:38  #15 
"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
7×509 Posts 
Silvester/Euclid sequence in factordb is repeatedly x^2x+1 until reaching a prime, I think the polynomial "x^2x+1" can be generalized to any irreducible polynomial with positive leading coefficient (can be added to factordb, users may enter the polynomial and the start number), e.g. 2*x+1, to get the Riesel problem, or 2*x1, to get the Sierpinski problem, etc.
Last fiddled with by sweety439 on 20210623 at 00:41 
20210624, 07:15  #16 
"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
110111101011_{2} Posts 
Silvester/Euclid sequence (and the sequences which I suggest in the previous post) should not stop when the number is not fully factored (e.g. n=20), and I think the sequence in factordb can add the generalization of A000945 and A000946 starting with given number n, e.g. A000945 starting with 12 is 12, 13, 157, 7, 5, 857221, 734826985621, 67, 36178036819339404422591341, 619, 196501174273319, ..., and A000946 starting with 12 is 12, 13, 157, 3499, 85697509, 1025850392947, 4054085938915939, 229936221387049265462828227782402791669, ..., A000945 should stop only when the number has no known prime factor, but A000946 should stop when the number is not fully factored.
Also A005265 and A005266 Last fiddled with by sweety439 on 20210624 at 07:19 
20210806, 08:38  #17 
"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
DEB_{16} Posts 
Also suggest to add:
* "unitary Aliquot sequence" (x > A063919(x), see A003062, A063991, and A097030) * "Aliquotlike sequence based on Dedekind psi function" (x > A306927(x), see A323327) * "exponential Aliquot sequence" (x > A126164(x), see A126165 and A054979) * "infinitary Aliquot sequence" (x > A126168(x), see A126169) * "biunitary Aliquot sequence" (x > A331970(x), see A292981) * "totient Aliquot sequence" (x > A092693(x), see A286233 for "totient amicable numbers" and see A343243 for "totient sociable numbers") These sequences can also use the sense of http://www.aliquotes.com/autres_proc...iteratifs.html (x > A001065(x)+k with fixed integer k) to generate, i.e. x > A063919(x)+k, x > A306927(x)+k, etc.) Besides, I think that factordb can include all numbers <=25 digits in database without new ID (currently factordb only include all numbers <=18 digits in database without new ID), also, factordb only show the first 10 digits and the last 2 digits for numbers >50 digits, I think that factordb can show the first 10 digits and the last 10 digits for numbers >50 digits. Last fiddled with by sweety439 on 20210806 at 09:12 
20210808, 04:56  #18 
"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
7×509 Posts 
Does factordb use Baillie–PSW primality test to test the PRPs? Also, it is known that if generalized Riemann hypothesis is true, then all numbers n which passed the Miller Rabin primality test to all bases b<(ln n)^4 are primes, so I suggest factordb can also run this test and add a status "GRHP", i.e. if generalized Riemann hypothesis is true, then this number is definitely prime.

20210809, 00:59  #19 
"Matthew Anderson"
Dec 2010
Oregon, USA
5·233 Posts 
Hi again,
I sent an email to the guy in charge of Factordb.com (Markus), asking him how he feels about batch submissions of prime integer factorizations of positive integers. Markus Tervooren (markustervooren [a] web.de) did not reply to me, and I do not plan on emailing him again. He is probably a busy guy. I feel factordb.com is a valuable service. A few people want to look up prime integer factroizations, and do not have computers set up to do it themselves. If anyone else wants to contact Markus, that is okay. Regards, Matt Last fiddled with by Uncwilly on 20210809 at 01:26 Reason: broke email address 
20210811, 16:49  #20  
Feb 2017
Nowhere
1011011111111_{2} Posts 
Quote:
E. Bach, Explicit bounds for primality testing and related problems, Math. Comp. 55 (1990), 355–380 Using Bach's bound for n around 10^{1000}, it would require over 700000 MillerRabin tests. So for large numbers, it would be a lot of bucks for not much bang. EDIT: The number 700000 is a gross understatement. It's roughly the number of prime bases less than Bach's bound. That would be fine for the simple Fermat test. With RabinMiller, though, it's not enough. It is possible to have n "pass" the test with prime bases p and q, but not to the base p*q. This can happen as follows: Suppose m = (n1)/2^{k} is even, p^{2m} == q^{2m} == 1 (mod n), and p^{m} == q^{m} == 1 (mod n). Then (pq)^{m} == 1 (mod n). Note, however, that [using the hypothesis that m is even] p^{m/2} and q^{m/2} are square roots of 1 (mod n). If they are neither equal nor equal and opposite, then n is composite (more than two square roots of 1 (mod n)), and p*q is a "witness." Last fiddled with by Dr Sardonicus on 20210812 at 13:03 Reason: clarification 

20220608, 18:21  #21 
"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
7×509 Posts 
Nice news!!!
I found a way to add many numbers in a sequence to factordb by one click!!! First, enter a noncomplete factored number (say the Fermat number F12) Second, copy the bfile in OEIS (for the sequence you want to add) and paste the full bfile to the "report factors" box. Then all numbers in this bfile will be added!!! I used this way to add all numbers in these sequences: A000110 Bell numbers (I copied this afile instead of the bfile, since this afile has 3016 terms (a(0) to a(3015)) A000111 Euler zigzag numbers A000670 Fubini numbers A001006 Motzkin numbers A000041 partition numbers (but all numbers in this sequence seems to be already in factordb ....) A000009 distinct partition numbers A003422 left factorial numbers (since the bfile has only 100 terms, thus I used PARI/GP to compute more terms and copied them to factordb) A005165 alternating factorial numbers (since the bfile has only 100 terms, thus I used PARI/GP to compute more terms and copied them to factordb) A000108 Catalan numbers (although I know that this numbers are trivially 100% factored, like the factorial numbers and the primorial numbers) A000105 polyomino numbers A000602 alkane numbers A000073 tribonacci numbers A000078 tetranacci numbers A000129 Pell numbers A006190 3Fibonacci numbers A002315 NSW numbers A000931 Padovan numbers A000930 Narayana numbers A001608 Perrin numbers A001008 1Wolstenholme numbers A007406 2Wolstenholme numbers A000521 elliptic modular invariant J(tau) A000594 Ramanujan's tau numbers (the most exciting!!! The bfile has 16090 terms (thus of course, after I added them, I get "You have reached your hourly limit of 6000 IDs created.", but you must remove the "" for the negative numbers in the bfile, since factordb does not support negative numbers and not add their absolute values) 
20220608, 18:35  #22 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
9,901 Posts 

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