20211019, 00:28  #1 
"Vincent"
Apr 2010
Over the rainbow
101100100111_{2} Posts 
birthday date, all format *2^n+1
24051981
Code:
24051981*2^24+1 (15 digits) 24051981*2^49+1 (23 digits) 24051981*2^53+1 (24 digits) 24051981*2^55+1 (24 digits) 24051981*2^71+1 (29 digits) 24051981*2^99+1 (38 digits) 24051981*2^104+1 (39 digits) 24051981*2^133+1 (48 digits) 24051981*2^144+1 (51 digits) 24051981*2^280+1 (92 digits) 24051981*2^323+1 (105 digits) 24051981*2^336+1 (109 digits) 24051981*2^435+1 (139 digits) 24051981*2^724+1 (226 digits) 24051981*2^1381+1 (424 digits) 24051981*2^2003+1 (611 digits) 24051981*2^2248+1 (685 digits) 24051981*2^2344+1 (713 digits) 24051981*2^2895+1 (879 digits) 24051981*2^3460+1 (1049 digits) 24051981*2^3913+1 (1186 digits) 24051981*2^5879+1 (1778 digits) 24051981*2^7393+1 (2233 digits) 24051981*2^8801+1 (2657 digits) 24051981*2^10837+1 (3270 digits) 24051981*2^11605+1 (3501 digits) 24051981*2^12496+1 (3770 digits) 24051981*2^12985+1 (3917 digits) 24051981*2^22380+1 (6745 digits) 24051981*2^28043+1 (8450 digits) 24051981*2^32917+1 24051981*2^36895+1 24051981*2^46464+1 24051981*2^53425+1 24051981*2^60953+1 24051981*2^95923+1 24051981*2^124421+1 24051981*2^226056+1 24051981*2^233387+1 Code:
19810524*2^38+1 19810524*2^46+1 19810524*2^47+1 19810524*2^53+1 19810524*2^67+1 19810524*2^83+1 19810524*2^101+1 19810524*2^259+1 19810524*2^281+1 19810524*2^1085+1 19810524*2^1586+1 19810524*2^2405+1 19810524*2^2867+1 19810524*2^2918+1 19810524*2^2933+1 19810524*2^3479+1 19810524*2^4379+1 19810524*2^4823+1 19810524*2^5470+1 19810524*2^6125+1 19810524*2^7349+1 19810524*2^10159+1 19810524*2^10786+1 19810524*2^12065+1 19810524*2^20830+1 19810524*2^27110+1 19810524*2^55985+1 19810524*2^134999+1 19810524*2^169943+1 Code:
5241981*2^21+1 5241981*2^29+1 5241981*2^35+1 5241981*2^45+1 5241981*2^80+1 5241981*2^1119+1 5241981*2^1188+1 5241981*2^1268+1 5241981*2^1373+1 5241981*2^3288+1 5241981*2^3429+1 5241981*2^4035+1 5241981*2^5189+1 5241981*2^5700+1 5241981*2^12680+1 5241981*2^25260+1 5241981*2^37989+1 Last fiddled with by firejuggler on 20211019 at 01:23 
20211019, 04:58  #2 
Mar 2006
Germany
3·991 Posts 
Please give search ranges for the nvalues done.

20211019, 12:02  #3 
"Vincent"
Apr 2010
Over the rainbow
101100100111_{2} Posts 
i'm not done, of course, but I intend to fgo to 1e6

20211019, 13:18  #4 
Feb 2017
Nowhere
2·29·103 Posts 
You did say, all format.
So, I entered the date May 24, 1981 AD (Gregorian calendar) into a Julian Day calculator. Modified Julian Day 44,748 November 17. 1858 AD Julian Day 2,444,748.5 noon on January 1. 4713 BC I wasn't sure about the rounding, so... 44747*2^3 + 1 44747*2^131 + 1 44748*2^4 + 1 44748*2^8 + 1 44748*2^20 + 1 44748*2^24 + 1 44748*2^33 + 1 44748*2^48 + 1 44748*2^49 + 1 44748*2^60 + 1 44749*2^10 + 1 44749*2^46 + 1 44749*2^118 + 1 44749*2^186 + 1 2444747*2^7 + 1 2444747*2^75 + 1 2444747*2^119 + 1 2444747*2^127 + 1 2444748*2^1 + 1 2444748*2^4 + 1 2444748*2^40 + 1 2444748*2^52 + 1 2444748*2^100 + 1 2444748*2^124 + 1 2444748*2^154 + 1 2444748*2^192 + 1 2444749*2^2 + 1 2444749*2^194 + 1 
20211019, 15:49  #5 
"Vincent"
Apr 2010
Over the rainbow
101100100111_{2} Posts 
did you check if they were gfn?

20211020, 12:38  #6 
Feb 2017
Nowhere
2·29·103 Posts 

20211020, 12:48  #7 
"Oliver"
Sep 2017
Porta Westfalica, DE
2^{3}·11·13 Posts 
GFN means most likely Generalized Fermat Numbers in this context.

20211020, 13:12  #8  
Feb 2017
Nowhere
2×29×103 Posts 
Quote:
One type of GFN is a^(2^{k}) + 1, which none of the examples in this thread appear to be. Another type of GFN is a^(2^{k}) + b^(2^{k}). I didn't check whether any examples in this thread are of that type. All I checked was that the examples I posted had not tested composite with a BPSW test. 

20211020, 14:04  #9 
Mar 2006
Germany
3·991 Posts 
None of your given small primes are a divisor of any Generalized Fermat number.
Last fiddled with by kar_bon on 20211020 at 14:05 
20211020, 15:10  #10 
"Mark"
Apr 2003
Between here and the
2^{2}·3^{2}·11·17 Posts 
What date formats? I can think of these (and there are likely more):
yyyymmdd (my personal favorite as it cannot easily be read incorrectly) mmddyyyy (format popular in the US) ddmmyyyy (format popular outside of the US) yyyyjjj (jjj is the Julian day of the year) And for those who don't care about the century: yymmdd mmddyy ddmmyy yyjjj Last fiddled with by rogue on 20211020 at 15:11 
20211020, 17:11  #11 
"Vincent"
Apr 2010
Over the rainbow
5×571 Posts 
I will contend with the first three for now.
iso 8601 format , european format and USA format. also http://www.fermatsearch.org/news.html Last fiddled with by firejuggler on 20211020 at 17:13 
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