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 A361813 #7 Mar 25 2023 08:19:19
%S A361813 1,2,14,80,486,3030,19184,122924,794678,5173160,33863666,222683588,
%T A361813 1469908848,9733916596,64636957300,430240178484,2869778018070,
%U A361813 19177245746844,128361805431752,860443079597872,5775392952659170,38811408514848032,261101034656317244
%N A361813 Expansion of 1/sqrt(1 - 4*x*(1+x)^4).
%F A361813 a(n) = Sum_{k=0..n} binomial(2*k,k) * binomial(4*k,n-k).
%F A361813 n*a(n) = 2 * ( (2*n-1)*a(n-1) + 4*(2*n-2)*a(n-2) + 6*(2*n-3)*a(n-3) + 4*(2*n-4)*a(n-4) + (2*n-5)*a(n-5) ) for n > 4.
%o A361813 (PARI) my(N=30, x='x+O('x^N)); Vec(1/sqrt(1-4*x*(1+x)^4))
%Y A361813 Cf. A006139, A137635, A360133, A361790, A361791, A361792, A361812, A361814.
%K A361813 nonn
%O A361813 0,2
%A A361813 _Seiichi Manyama_, Mar 25 2023