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 A172402 #2 Mar 30 2012 18:37:21
%S A172402 1,1,3,16,166,3464,146167,12437880,2127406440,729774938584,
%T A172402 501412103054958,689540993399039000,1897244652767973627366,
%U A172402 10442429807446111573892528,114961543001288361817819197405
%N A172402 G.f.: 1/(1-x) = Sum_{n>=0} a(n)*x^n/(1+x)^(2^(n+1)-2).
%F A172402 Column 1 of triangle A172400.
%e A172402 1/(1-x) = 1 + x/(1+x)^2 + 3*x^2/(1+x)^6 + 16*x^3/(1+x)^14 + 166*x^4/(1+x)^30 +...
%o A172402 (PARI) {a(n)=if(n==0,1,polcoeff(-(1-x)*sum(m=0,n-1,a(m)*x^m/(1+x +x*O(x^n))^(2^(m+1)-2)),n))}
%Y A172402 Cf. A172400, A172401, A172403.
%K A172402 nonn
%O A172402 0,3
%A A172402 _Paul D. Hanna_, Feb 01 2010