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 A049214 #22 Aug 13 2024 14:36:45
%S A049214 1,20,784,52352,5360256,782525952,154594381824,39746508226560,
%T A049214 12902483299368960,5162443736924160000,2496471943395999744000,
%U A049214 1435556519572510605312000,968234590214616380866560000
%N A049214 Scaled coefficients of (arctanh x)^3.
%F A049214 E.g.f.: (arctanh x)^3 or (1-x^2)^-1 * (arctanh x)^2.
%F A049214 a(n) is coefficient of x^(2*n+3) in (arctanh x)^3, multiplied by (2*n+3)!/6.
%F A049214 a(n) = (1/4)* Sum_{p=1..2*n+2} binomial(2*n+1,p-1) Sum_{m=3..2*n+3} binomial(m,3)*abs(s(2*n+3,m))*((-p)^(m-3)+(-p)^(m-3)) where s(n,m) is Stirling number of first kind . - _Ammar Khatab_, Aug 13 2024
%e A049214 (arctanh x)^3 = x^3 + x^5 + 14/15*x^7 + 818/945*x^9 + ...
%t A049214 a[n_] := SeriesCoefficient[ArcTanh[x]^3, {x, 0, 2n+3}]*(2n+3)!/6;
%t A049214 a /@ Range[0, 12] (* _Jean-François Alcover_, Mar 26 2021 *)
%Y A049214 Cf. A049215, A049216, A049217.
%K A049214 nonn
%O A049214 0,2
%A A049214 Joe Keane (jgk(AT)jgk.org)