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 A141761 #2 Mar 30 2012 18:37:11
%S A141761 1,1,1,2,6,26,154,1188,11474,134432,1863168,29936846,548625820,
%T A141761 11315025894,259733293774,6574304470320,182050022755386,
%U A141761 5477819548007438,178054691097463354,6220193033111607018
%N A141761 Column 0 of triangle A141760.
%C A141761 Also equals column 1 (shifted) of triangle A141760.
%F A141761 G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n/(1+x)^{n*(n-1)/2}.
%F A141761 a(n) = 1 - Sum_{j=0..n-1} a(j) * (-1)^(n-j) * C(j(j-1)/2 + n-j-1, n-j) for n>0, with a(0)=1.
%o A141761 (PARI) {a(n)=if(n==0,1,1 - sum(j=0,n-1,a(j)*(-1)^(n-j)*binomial(j*(j-1)/2+n-j-1,n-j)))}
%Y A141761 Cf. A141760, A141762, A141763, A141764.
%K A141761 nonn
%O A141761 0,4
%A A141761 _Paul D. Hanna_, Jul 18 2008