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 A196867 #5 Mar 30 2012 18:37:31
%S A196867 1,4,40,-544,-14240,240512,7905536,-144081920,-5248825856,99459618816,
%T A196867 3842132979712,-74547398033408,-2991092285194240,58965437254402048,
%U A196867 2429529032173420544,-48445417122664284160,-2035619492638819483648,40941665274780773253120
%N A196867 G.f. A(x) satisfies: A(x)^-4 + A(-x)^-4 = 2 and A(x)^4 - A(-x)^4 = 32*x.
%F A196867 G.f.: ( (sqrt(1+4*4^4*x^2) + 2*4^2*x)*(sqrt(1+4*4^4*x^2) + 1)/2 )^(1/8).
%e A196867 G.f.: A(x) = 1 + 4*x + 40*x^2 - 544*x^3 - 14240*x^4 + 240512*x^5 +...
%e A196867 where
%e A196867 A(x)^4 = 1 + 16*x + 256*x^2 - 65536*x^4 + 33554432*x^6 +...
%e A196867 A(x)^-4 = 1 - 16*x + 4096*x^3 - 2097152*x^5 + 1342177280*x^7 +...
%o A196867 (PARI) {a(n)=local(A=[1,4]);for(k=2,n,A=concat(A,0);if(k%2==1,A[#A]=-Vec(Ser(A)^4)[#A]/4,A[#A]=Vec(Ser(A)^-4)[#A]/4));A[n+1]}
%o A196867 (PARI) {a(n)=local(X=x+x*O(x^n));polcoeff(((sqrt(1+4*4^4*X^2) + 2*4^2*x)*(sqrt(1+4*4^4*X^2) + 1)/2 )^(1/8),n)}
%Y A196867 Cf. A196866, A193618, A193619, A196864, A196865, A196868, A196869.
%K A196867 sign
%O A196867 0,2
%A A196867 _Paul D. Hanna_, Oct 06 2011