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 A369077 #11 Jan 13 2024 10:47:59 %S A369077 1,0,0,-2,-2,-2,13,32,55,-72,-439,-1152,-506,4870,20613,31744,-26392, %T A369077 -313096,-826529,-654362,3635175,16431826,30100349,-15474300, %U A369077 -262654439,-780688624,-756130333,3013376172,15711713509,31584466782,-6090973971,-250819494954 %N A369077 Expansion of (1/x) * Series_Reversion( x * (1+x^3/(1-x))^2 ). %H A369077 <a href="/index/Res#revert">Index entries for reversions of series</a> %F A369077 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} (-1)^k * binomial(2*n+k+1,k) * binomial(n-2*k-1,n-3*k). %o A369077 (PARI) my(N=40, x='x+O('x^N)); Vec(serreverse(x*(1+x^3/(1-x))^2)/x) %o A369077 (PARI) a(n, s=3, t=2, u=-2) = sum(k=0, n\s, (-1)^k*binomial(t*(n+1)+k-1, k)*binomial((t+u+1)*(n+1)-(s-1)*k-2, n-s*k))/(n+1); %Y A369077 Cf. A168491, A369076. %Y A369077 Cf. A368970, A368974, A368976. %Y A369077 Cf. A369011. %K A369077 sign %O A369077 0,4 %A A369077 _Seiichi Manyama_, Jan 12 2024