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 A381774 #8 Mar 07 2025 10:49:01
%S A381774 1,2,19,255,3995,68344,1237526,23316295,452385355,8977539540,
%T A381774 181374792040,3718002102747,77138798530854,1616741658725930,
%U A381774 34179703551312530,728019711835819493,15608122038151106507,336551042553481867640,7293934071668996347055
%N A381774 Expansion of ( (1/x) * Series_Reversion( x/((1+x) * C(x))^4 ) )^(1/4), where C(x) is the g.f. of A000108.
%F A381774 G.f. A(x) satisfies A(x) = (1 + x*A(x)^4) * C(x*A(x)^4).
%F A381774 a(n) = Sum_{k=0..n} binomial(4*n+2*k+1,k) * binomial(4*n+1,n-k)/(4*n+2*k+1).
%o A381774 (PARI) my(N=20, x='x+O('x^N)); Vec((serreverse(x/((1+x)*(1-sqrt(1-4*x))/(2*x))^4)/x)^(1/4))
%Y A381774 Cf. A054727, A060941, A381772, A381773, A381775.
%Y A381774 Cf. A000108.
%K A381774 nonn
%O A381774 0,2
%A A381774 _Seiichi Manyama_, Mar 07 2025