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 A386210 #18 Jul 16 2025 10:04:01
%S A386210 1,3,12,76,687,7917,108928,1725768,30796797,609902671,13260956196,
%T A386210 313951142508,8039710476955,221467222589241,6531522562100448,
%U A386210 205381223316464464,6860540121003113913,242651957254699927803,9060531236377877408956,356208300597443254526892
%N A386210 G.f. A(x) satisfies A(x) = 1/(1-x)^3 + x^2 * (d/dx A(x)^2).
%F A386210 a(n) = binomial(n+2,2) + (n-1) * Sum_{k=0..n-1} a(k) * a(n-1-k).
%F A386210 a(n) = binomial(n+2,2) + 2 * Sum_{k=0..n-1} k * a(k) * a(n-1-k).
%o A386210 (PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=binomial(i+2, 2)+(i-1)*sum(j=0, i-1, v[j+1]*v[i-j])); v;
%Y A386210 Cf. A386208, A386209.
%Y A386210 Cf. A386212.
%K A386210 nonn
%O A386210 0,2
%A A386210 _Seiichi Manyama_, Jul 15 2025