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 A194603 #25 Jun 03 2015 18:37:10
%S A194603 2,3,2,3,11,5,13,7,17,11,23,11,53,13,29,17,67,17,37,19,41,23,47,23,
%T A194603 101,53,53,29,59,29,61,31,67,67,71,37,73,37,79,41,83,41,173,43,89,47,
%U A194603 751,47,97,101,101,53,107,53,109,113,113,59,1889,59,487,61,127
%N A194603 Smallest prime either of the form n*2^k - 1 or n*2^k + 1, k >= 0, or 0 if no such prime exists.
%C A194603 Primes arising from A194591 (or 0 if no such prime exists).
%C A194603 Many of these terms are in A093868.
%H A194603 Arkadiusz Wesolowski, <a href="/A194603/b194603.txt">Table of n, a(n) for n = 1..1000</a>
%e A194603 For n=7, 7*2^0-1 and 7*2^0+1 are composite, but 7*2^1-1=13 is prime, so a(7)=13.
%t A194603 Table[k = 0; While[! PrimeQ[a = n*2^k - 1] && ! PrimeQ[a = n*2^k + 1], k++]; a, {n, 100}] (* _Arkadiusz Wesolowski_, Sep 04 2011 *)
%t A194603 n2k[n_]:=Module[{k=0},While[NoneTrue[n*2^k+{1,-1},PrimeQ],k++];SelectFirst[ n*2^k+{-1,1},PrimeQ]]; Array[n2k,70] (* The program uses the NoneTrue and SelectFirst functions from Mathematica version 10 *) (* _Harvey P. Dale_, Jun 03 2015 *)
%Y A194603 Cf. A194591, A194600, A194606, A194607, A194608, A194635, A194636, A194637, A194638, A194639.
%Y A194603 Cf. A038699, A050921, A076335, A180247.
%K A194603 nonn
%O A194603 1,1
%A A194603 _Arkadiusz Wesolowski_, Aug 30 2011