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 A107701 #3 Mar 30 2012 18:36:46
%S A107701 1,2,4,6,4,-6,-8,44,52,-520,-580,8628,9312,-188326,-199136,5210560,
%T A107701 5435860,-178308938,-184306176,7409693156,7608810060,-368330924160,
%U A107701 -376418726640,21620184591972,22015468707328,-1481473941622200,-1504385498284500,117304374434860032
%N A107701 Self-COMPOSE of A107700; thus g.f. A(x) = G(G(x)) = x + 2*G(x)^2, where G(x) is the g.f. of A107700.
%F A107701 G.f. satisfies: A(-A(-x)) = x.
%o A107701 (PARI) {a(n)=local(A,B,F);A=x+x^2+x*O(x^n);if(n<1,0, for(i=0,n,F=x+2*A^2;B=serreverse(A);A=(A+subst(B,x,F))/2); polcoeff(x+2*A^2,n,x))}
%Y A107701 Cf. A107699, A107700.
%K A107701 sign
%O A107701 1,2
%A A107701 _Paul D. Hanna_, May 21 2005