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 A115137 #10 May 22 2013 05:47:18
%S A115137 1,1,7,41,247,1545,9975,66057,446455,3067913,21372919,150618121,
%T A115137 1071841271,7691763721,55600938999,404488323081,2959189475319,
%U A115137 21757613309961,160691417776119,1191577871450121,8868160862158839
%N A115137 Second diagonal of triangle A113647 (called Y(2,1)).
%H A115137 Vincenzo Librandi, <a href="/A115137/b115137.txt">Table of n, a(n) for n = 0..300</a>
%F A115137 a(n)= b(n) - 2*b(n-1) with b(n):=A062992(n)= A064062(n+1), n>=1. a(0):=1.
%F A115137 G.f.: (1-2*x)*(2*c(2*x)-1)/(1+x) with c(x) g.f. of A000108 (Catalan).
%F A115137 a(n)= A113647(n, n), n>=1.
%F A115137 Recurrence: (n-2)*(n+1)*a(n) = (7*n^2-19*n+14)*a(n-1) + 4*(n-1)*(2*n-3)*a(n-2). - _Vaclav Kotesovec_, Oct 19 2012
%F A115137 a(n) ~ 2^(3*n+2)/(3*sqrt(Pi)*n^(3/2)). - _Vaclav Kotesovec_, Oct 19 2012
%e A115137 41=a(3)= A062992(3) - 2*A062992(2) = 67 - 2*13.
%t A115137 CoefficientList[Series[(1-2*x)*(2*(1-Sqrt[1-8*x])/(4*x)-1)/(1+x), {x, 0, 20}], x] (* _Vaclav Kotesovec_, Oct 19 2012 *)
%K A115137 nonn,easy
%O A115137 0,3
%A A115137 _Wolfdieter Lang_, Jan 13 2006