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 A137572 #3 Mar 30 2012 18:37:09
%S A137572 1,3,16,100,681,4908,36842,285158,2260257,18257902,149769225,
%T A137572 1244277499,10448404901,88538107802,756153001241,6501989278168,
%U A137572 56244305146039,489111092027854,4273491476147117,37496699100314116,330261353255659842
%N A137572 The first upper diagonal of square array A137570; equals the convolution of the main diagonal A137571 with A002293.
%F A137572 G.f. A(x) = F(x)/(1 - x*C(x)*F(x)^2 - x*F(x)^3), where C(x) = 1 + xC(x)^2 is g.f. of Catalan numbers (A000108) and F(x) = 1 + xF(x)^4 is g.f. of A002293.
%e A137572 G.f.: A(x) = 1 + 3*x + 16*x^2 + 100*x^3 + 681*x^4 + 4908*x^5 +...;
%e A137572 A(x) = F(x)/(1 - x*C(x)*F(x)^2 - x*F(x)^3), where
%e A137572 C(x) = 1 + xC(x)^2 is g.f. of Catalan numbers (A000108):
%e A137572 [1, 1, 2, 5, 14, 42, 132, 429, 1430, ..., C(2n,n)/(n+1), ...] and
%e A137572 F(x) = 1 + xF(x)^4 is g.f. of A002293:
%e A137572 [1, 1, 4, 22, 140, 969, 7084, 53820, ..., C(4n,n)/(3n+1), ...].
%o A137572 (PARI) {a(n)=local(m=n+1,C,F,A); C=Ser(vector(m,r,binomial(2*r-2,r-1)/r)); F=Ser(vector(m,r,binomial(4*r-4,r-1)/(3*r-2))); A=F/(1-x*C*F^2-x*F^3);polcoeff(A+O(x^m),n,x)}
%Y A137572 Cf. A137570, A137571, A137573; A000108, A002293.
%K A137572 nonn
%O A137572 0,2
%A A137572 _Paul D. Hanna_, Jan 27 2008