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 A113303 #5 Mar 30 2012 17:22:41
%S A113303 0,2,0,3,0,0,5,4,0,0,0,0,8,9,6,0,0,0,0,0,9,0,0,0,0,0,0,26,47,12,0,7,0,
%T A113303 0,0,0,0,0,0,28,44,0,31,51,0,61,0,0,0,0,27,0,0,0,0,0,89,0,90,135,98,
%U A113303 48,122,120,0,0,0,0,121,0,0,0,0,112,0,91,0,0,55,63,133,48,0,0,126,179,0,78
%N A113303 Least number k such that prime(n) divides T(k), the central trinomial coefficient A002426(k), or 0 if there is no such k.
%C A113303 When a(n)=0, prime(n) is in A113305. When a(n)>0, prime(n) is in A113304.
%H A113303 T. D. Noe, <a href="/A113303/b113303.txt">Table of n, a(n) for n=1..1000</a>
%t A113303 nn=1000; a=b=1; t=Join[{1}, Table[c=((2n-1)b+3(n-1)a)/n; a=b; b=c; c, {n, 2, nn}]]; Table[p=Prime[i]; k=1; While[k<nn && Mod[t[[k]], p]>0, k++ ]; If[k==nn, 0, k], {i, PrimePi[nn]}]
%Y A113303 Cf. A113302 (number of k for which prime(n) divides T(k)).
%K A113303 nonn
%O A113303 1,2
%A A113303 _T. D. Noe_, Oct 24 2005