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 A107086 #15 Nov 07 2019 05:25:41
%S A107086 1,1,-1,2,-5,13,-35,99,-289,857,-2578,7864,-24252,75430,-236348,
%T A107086 745431,-2364399,7536482,-24127482,77544613,-250098478,809169322,
%U A107086 -2625483810,8541037140,-27851360659,91018956200,-298052119611,977825373366,-3213513271929,10577811289462,-34870732260397
%N A107086 G.f. A(x) satisfies: A(x)^4 = A(x^2)^2 + 4*x.
%C A107086 Self-convolution is A107087. Self-convolution 4th power is A107088.
%H A107086 Paul D. Hanna, <a href="/A107086/b107086.txt">Table of n, a(n) for n = 0..1000</a>
%e A107086 A(x)^4 = 1 + 4*x + 2*x^2 - x^4 + 2*x^6 - 5*x^8 + 12*x^10 - 30*x^12 +...
%e A107086 A(x^2)^2 = 1 + 2*x^2 - x^4 + 2*x^6 - 5*x^8 + 12*x^10 - 30*x^12 +...
%t A107086 nmin = 0; nmax = 30; sol = {a[0] -> 1};
%t A107086 Do[A[x_] = Sum[a[k] x^k, {k, 0, n}] /. sol; eq = CoefficientList[A[x]^4 - A[x^2]^2 - 4x + O[x]^(n+1), x][[2;;]] == 0 /. sol; sol = sol ~Join~ Solve[eq][[1]], {n, 2, nmax}];
%t A107086 a /@ Range[nmin, nmax] /. sol (* _Jean-François Alcover_, Nov 07 2019 *)
%o A107086 (PARI) {a(n)=local(A=1+x); for(i=1, n, A=(subst(A, x, x^2)^2+4*x+x*O(x^n))^(1/4)); polcoeff(A, n, x)}
%o A107086 for(n=0,40,print1(a(n),", "))
%Y A107086 Cf. A107087, A107088, A187814, A228711.
%K A107086 sign
%O A107086 0,4
%A A107086 _Paul D. Hanna_, May 11 2005