%I #18 Feb 09 2024 08:44:08
%S 1,3,24,330,6552,171360,5581440,218045520,9945936000,519177859200,
%T 30535045632000,1998518736614400,144098325316915200,
%U 11350405033583616000,969837188805041356800,89351761457237190912000,8830056426362263572480000,931769828125956695715840000
%N a(n) = 3*(3*n+2)!/(2*n+3)!.
%F E.g.f.: exp( Sum_{k>=1} binomial(3*k,k) * x^k/k ).
%F a(n) = 3*A076151(n+1) for n > 0.
%F a(n) = A000142(n)*A001764(n+1). - _Alois P. Heinz_, Feb 08 2024
%o (PARI) a(n) = 3*(3*n+2)!/(2*n+3)!;
%Y Cf. A001763, A370054.
%Y Cf. A065866, A370058.
%Y Cf. A076151.
%Y Cf. A000142, A001764.
%K nonn
%O 0,2
%A _Seiichi Manyama_, Feb 08 2024
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