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 A191618 #9 Aug 03 2014 14:01:31
%S A191618 0,1,1,1,2,1,11,2,2,1,13,2,4,22,2,1,2,2,43,4,2,13,2,1,13,1,2,46,8,29,
%T A191618 83,2,8,34,1,11,19,31,25,7,38,31,31,76,52,31,43,32,13,92,2,1,59,22,1,
%U A191618 16,19,11,16,74,8,13,8,74,2,121,20,49,85,134,116,16
%N A191618 Least a such that (2^n+a)*2^n - 1 is prime.
%H A191618 Pierre CAMI, <a href="/A191618/b191618.txt">Table of n, a(n) for n = 1..5000</a>
%t A191618 Table[a = 0; While[! PrimeQ[(2^n + a)*2^n - 1], a++]; a, {n, 100}] (* _T. D. Noe_, Jun 11 2011 *)
%Y A191618 Cf. A191617, A191619, A191620, A191621.
%K A191618 nonn
%O A191618 1,5
%A A191618 _Pierre CAMI_, Jun 09 2011