This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A127587 #14 Dec 17 2016 03:57:44
%S A127587 2,1,0,0,1,0,1,0,4,6,4,2,1,0,4,3,1,0,1,0,13,6,25,12,38,21,10,15,7,3,1,
%T A127587 0,4,5,2,23,11,5,2,24,23,11,5,2,13,6,19,9,4,18,10,20,19,9,4,2,31,15,7,
%U A127587 3,1,0,11,5,2,66,62,42,62,39,19,9,4,14,11,5,2,54,46,29,14,29,14,63,31,15,7
%N A127587 Smallest nonnegative integer k such that (k+1)*2^n-1 is prime.
%C A127587 The associated prime number list is (k+1)*2^n-1 = 2,3,3,7,31,31,127,127,1279,3583,5119,6143,... for n=0,1,2,3,4,... - _R. J. Mathar_, Jan 22 2007
%H A127587 Harvey P. Dale, <a href="/A127587/b127587.txt">Table of n, a(n) for n = 0..1000</a>
%F A127587 a[A000043(j)]=0 for j=1,2,3,4,... - _R. J. Mathar_, Jan 22 2007
%F A127587 a(n) = A085427(n) - 1. - _Filip Zaludek_, Dec 16 2016
%p A127587 A127587 := proc(n) local k; k:=0 ; while true do if isprime( (k+1)*2^n-1) then RETURN(k) ; fi ; k := k+1 ; od ; end: for n from 0 to 100 do printf("%d, ",A127587(n)) ; od ; # _R. J. Mathar_, Jan 22 2007
%t A127587 a = {}; Do[k = 0; While[ ! PrimeQ[k 2^n + 2^n - 1], k++ ]; AppendTo[a, k], {n, 0, 50}]; a
%Y A127587 Cf. A007522, A127575, A127576, A127577, A127578, A127580, A127581, A087522, A127586.
%K A127587 nonn
%O A127587 0,1
%A A127587 _Artur Jasinski_, Jan 19 2007
%E A127587 More terms from _R. J. Mathar_, Jan 22 2007