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 A372126 #15 Nov 30 2024 08:50:05 %S A372126 1,1,5,11,95,150,2688,-111,98489,-215578,4416842,-18887063,230670421, %T A372126 -1356589436,13381147908,-92724422022,831047516316,-6277471705749, %U A372126 53925750947589,-426682784513559,3602138266461603,-29250145766625450,245524688963062050 %N A372126 G.f. A(x) satisfies A(x) = 1/( 1 - x*A(x)*(1 + 9*x*A(x))^(1/3) ). %H A372126 <a href="/index/Res#revert">Index entries for reversions of series</a> %F A372126 a(n) = (1/(n+1)) * Sum_{k=0..n} 9^(n-k) * binomial(n+k,k) * binomial(k/3,n-k). %F A372126 From _Seiichi Manyama_, Nov 30 2024: (Start) %F A372126 G.f.: exp( Sum_{k>=1} A378555(k) * x^k/k ). %F A372126 a(n) = (1/(n+1)) * [x^n] 1/(1 - x*(1 + 9*x)^(1/3))^(n+1). %F A372126 G.f.: (1/x) * Series_Reversion( x*(1 - x*(1 + 9*x)^(1/3)) ). (End) %o A372126 (PARI) a(n) = sum(k=0, n, 9^(n-k)*binomial(n+k, k)*binomial(k/3, n-k))/(n+1); %Y A372126 Cf. A001002, A372125. %Y A372126 Cf. A372013, A372136, A378555. %K A372126 sign %O A372126 0,3 %A A372126 _Seiichi Manyama_, Apr 20 2024