OFFSET
0,2
FORMULA
E.g.f.: exp( 2/3 * Sum_{k>=1} binomial(3*k,k) * x^k/k ).
From Seiichi Manyama, Aug 31 2024: (Start)
E.g.f. satisfies A(x) = 1/(1 - x*A(x))^2.
a(n) = 2 * Sum_{k=0..n} (2*n+2)^(k-1) * |Stirling1(n,k)|. (End)
PROG
(PARI) a(n) = 2*(3*n+1)!/(2*n+2)!;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 08 2024
STATUS
approved