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 A365120 #14 Dec 06 2024 06:58:54
%S A365120 1,2,5,18,70,294,1291,5864,27314,129766,626367,3063096,15143562,
%T A365120 75563924,380062186,1924840480,9807649900,50241194250,258597717591,
%U A365120 1336730670244,6936403057274,36119232561000,188677598254078,988464846388710,5192270327405662
%N A365120 G.f. A(x) satisfies A(x) = (1 + x / (1 - x*A(x))^2)^2.
%F A365120 If g.f. satisfies A(x) = (1 + x/(1 - x*A(x))^s)^t, then a(n) = Sum_{k=0..n} binomial(t*(n-k+1),k) * binomial(n+(s-1)*k-1,n-k)/(n-k+1).
%F A365120 G.f.: A(x) = B(x)^2 where B(x) is the g.f. of A367236. - _Seiichi Manyama_, Dec 06 2024
%o A365120 (PARI) a(n, s=2, t=2) = sum(k=0, n, binomial(t*(n-k+1), k)*binomial(n+(s-1)*k-1, n-k)/(n-k+1));
%Y A365120 Cf. A000108, A365121.
%Y A365120 Cf. A006013, A365118, A365123.
%Y A365120 Cf. A367236.
%K A365120 nonn
%O A365120 0,2
%A A365120 _Seiichi Manyama_, Aug 22 2023