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 A381418 #11 Feb 23 2025 08:20:57
%S A381418 1,2,12,126,1920,38594,966336,29013502,1016725248,40756464002,
%T A381418 1840019388416,92407718510206,5110719354064896,308687318601431618,
%U A381418 20219267260662005760,1427631259848921544702,108098847179804608299008,8738141126983786551626498,751078053821468153074155520
%N A381418 E.g.f. A(x) satisfies A(x) = exp( 2 * sin(x * A(x)) ).
%F A381418 E.g.f.: B(x)^2, where B(x) is the e.g.f. of A381417.
%F A381418 a(n) = 2 * Sum_{k=0..n} (2*n+2)^(k-1) * i^(n-k) * A136630(n,k), where i is the imaginary unit.
%o A381418 (PARI) a136630(n, k) = 1/(2^k*k!)*sum(j=0, k, (-1)^(k-j)*(2*j-k)^n*binomial(k, j));
%o A381418 a(n) = 2*sum(k=0, n, (2*n+2)^(k-1)*I^(n-k)*a136630(n, k));
%Y A381418 Cf. A136630, A381417.
%K A381418 nonn
%O A381418 0,2
%A A381418 _Seiichi Manyama_, Feb 23 2025