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 A386208 #15 Jul 16 2025 10:03:44
%S A386208 1,1,3,15,109,1029,11831,159595,2466073,42920585,830791243,
%T A386208 17706459431,412116616517,10403094478669,283137307529727,
%U A386208 8266131486719107,257710382446835761,8546074646120275473,300384437888406796051,11155675460369469443263,436506923733804200244509
%N A386208 G.f. A(x) satisfies A(x) = 1/(1-x) + x^2 * (d/dx A(x)^2).
%F A386208 a(n) = 1 + (n-1) * Sum_{k=0..n-1} a(k) * a(n-1-k).
%F A386208 a(n) = 1 + 2 * Sum_{k=0..n-1} k * a(k) * a(n-1-k).
%o A386208 (PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=1+(i-1)*sum(j=0, i-1, v[j+1]*v[i-j])); v;
%Y A386208 Cf. A386209, A386210.
%Y A386208 Cf. A143917, A185183, A376125.
%K A386208 nonn
%O A386208 0,3
%A A386208 _Seiichi Manyama_, Jul 15 2025