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 A381746 #19 Mar 06 2025 08:44:01
%S A381746 1,36,2586,235884,24284907,2689924444,312907382800,37699275223260,
%T A381746 4663450108073401,588854988193808392,75589352418472567340,
%U A381746 9834912295258236849604,1294095251234713917535805,171909332777340128148714400,23024035140764003881788203616
%N A381746 Expansion of exp( Sum_{k>=1} binomial(10*k-1,2*k) * x^k/k ).
%H A381746 Seiichi Manyama, <a href="/A381746/b381746.txt">Table of n, a(n) for n = 0..462</a>
%F A381746 G.f. A(x) satisfies A(x^2) = B(x) * B(-x), where B(x) is the g.f. of A118971.
%F A381746 a(n) = Sum_{k=0..2*n} (-1)^k * A118971(k) * A118971(2*n-k).
%F A381746 a(0) = 1; a(n) = (1/n) * Sum_{k=1..n} binomial(10*k-1,2*k) * a(n-k).
%F A381746 G.f.: B(x)^4, where B(x) is the g.f. of A381752.
%o A381746 (PARI) my(N=20, x='x+O('x^N)); Vec(exp(sum(k=1, N, binomial(10*k-1, 2*k)*x^k/k)))
%Y A381746 Cf. A079489, A381744, A381745.
%Y A381746 Cf. A118971, A381752.
%K A381746 nonn,easy
%O A381746 0,2
%A A381746 _Seiichi Manyama_, Mar 05 2025