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A370085
Expansion of e.g.f. exp( Sum_{k>=1} (3*k)! * (x/6)^k/k ).
2
1, 1, 21, 3421, 2232361, 4047831801, 16492042429501, 131524059703672021, 1862832637043775536721, 43582296764832433769579761, 1592318494850388661944336320101, 86870590496672779178378519636679501, 6822481321458299127004125050236325798521
OFFSET
0,3
FORMULA
a(0) = 1; a(n) = (n-1)! * Sum_{k=1..n} (3*k)! * a(n-k) / (6^k * (n-k)!).
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=1, N, (3*k)!*(x/6)^k/k))))
CROSSREFS
Cf. A370087.
Sequence in context: A326295 A078395 A340331 * A202980 A221722 A153833
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 08 2024
STATUS
approved