20200127, 07:31  #1 
Mar 2018
2^{2}·7·19 Posts 
primes of ther form 19*3*2^k+ or 1
I found only three primes of this form up to k=10.000. (k=2,8,18)
Are they finite? 
20200127, 07:56  #2 
Aug 2006
3×1,993 Posts 
There should be infinitely many. You can look at the residue classes and do an infinite product to guess how sparse they will be.

20200127, 13:59  #3  
Feb 2017
Nowhere
2×11×263 Posts 
Looks like the OP missed quite a few. If the intent was to find exponents on both lists, the exponent 10 is missing and the exponent 18 is wrong.
From the List of primes k*2^{n} + 1 for k < 300 we have for k = 19*3 = 57, Quote:
From the List of primes k*2^{n}  1 for k < 300, again for k = 19*3 = 57, Quote:
Last fiddled with by Dr Sardonicus on 20200127 at 14:24 Reason: w, misread multiplier, had to redo. 

Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Primes of the form (b+1)*b^n+1 and b^n+(b+1)  sweety439  sweety439  164  20220306 16:19 
pg primes of the form 41s+r  enzocreti  enzocreti  0  20190715 13:12 
Primes of the Form Mod(p,q) = Mod(x,q)  a1call  Miscellaneous Math  6  20181211 03:34 
Primes of the form n+phi(n)  carpetpool  carpetpool  3  20170126 01:29 
Primes of the form a^(2^n)+b^(2^n)  YuL  Math  21  20121023 11:06 