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 A099191 #3 Mar 30 2012 17:31:06
%S A099191 73,2,3,0,5,0,7,0,0,0,11,0,211,0,0,0,53,0,613,0,0,0,0,0,43,0,0,0,0,0,
%T A099191 0,0,0,0,0,0,0,0,0,0,23,0,241,0,0,0,0,0,13,0,0,0,251,0,0,0,0,0,653,0,
%U A099191 97,0,0,0,0,0,0,0,0,0,0,0,271,0,0,0,0,0,673,0,0,0,281,0,67,0,0,0,683,0,0,0,0
%N A099191 Smallest prime p such that p+n is twice its reversal, or 0 if impossible.
%e A099191 a(13) = 211 since 211+13 = 224 = 2*112. a(25) = 43 since 25+43 = 68 = 2*34.
%t A099191 f[n_] := Block[{k = 1}, While[p = Prime[k]; p + n != 2FromDigits[ Reverse[ IntegerDigits[ p]]] && k < 10^6, k++ ]; If[k == 10^6, 0, Prime[k]]]; Table[ f[n], {n, 75}]
%Y A099191 Cf. A099190.
%K A099191 base,nonn
%O A099191 1,1
%A A099191 _Robert G. Wilson v_, Oct 01 2004