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 A367258 #10 Nov 11 2023 13:55:29 %S A367258 1,1,3,10,39,162,708,3202,14867,70448,339324,1656443,8176968,40749277, %T A367258 204727198,1035837256,5273360195,26992906495,138840628986, %U A367258 717245323961,3719765478096,19359725932165,101083353127371,529341453000447,2779470724644476,14630696492685339 %N A367258 G.f. satisfies A(x) = 1 + x*A(x) * (1 + x*A(x)^2)^2. %F A367258 If g.f. satisfies A(x) = 1 + x*A(x)^t * (1 + x*A(x)^u)^s, then a(n) = Sum_{k=0..n} binomial(t*k+u*(n-k)+1,k) * binomial(s*k,n-k) / (t*k+u*(n-k)+1). %o A367258 (PARI) a(n, s=2, t=1, u=2) = sum(k=0, n, binomial(t*k+u*(n-k)+1, k)*binomial(s*k, n-k)/(t*k+u*(n-k)+1)); %Y A367258 Cf. A000108. %K A367258 nonn %O A367258 0,3 %A A367258 _Seiichi Manyama_, Nov 11 2023