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 A188898 #12 Mar 30 2012 17:22:57
%S A188898 8,2,81,25,6,9,2,0,7,4,3,9,22,2,49,4,8,0,17,9,81,5,2,25,46,3,10,121,6,
%T A188898 9,18,4,31,2,11,169,7,6,1681,49,8,4,4961,12,225,8,2,16,32,0,49,25,17,
%U A188898 13,289,9,49,7,27,81,118,2,136161,196,14,4,10,841,1521
%N A188898 The index of the least n-gonal number greater than 1 that is also square, or 0 if none exists.
%C A188898 Sequence A188896 gives the n that have no solution.
%F A188898 If n is a square, then a(n)=2.
%t A188898 kMax = 25000; NgonIndex[n_, v_] := (-4 + n + Sqrt[16 - 8*n + n^2 - 16*v + 8*n*v])/(n - 2)/2; Table[k = 2; While[sqr = k^2; i = NgonIndex[n, sqr]; k < kMax && ! IntegerQ[i], k++]; If[k == kMax, k = sqr = i = 0]; i, {n, 3, 64}]
%Y A188898 Cf. A100252 (least square n-gonal number greater than 1).
%K A188898 nonn
%O A188898 3,1
%A A188898 _T. D. Noe_, Apr 13 2011