A363442 G.f. satisfies A(x) = exp( Sum_{k>=1} (-1)^(k+1) * A(x^k) * (3*x)^k/k ).

1, 3, 9, 54, 270, 1620, 9828, 61884, 397062, 2597508, 17232831, 115722918, 784996434, 5371325217, 37029240315, 256948639344, 1793271890988, 12579466538187, 88645665923244, 627235978623318, 4454619888380355, 31743030458459169, 226890102674671245

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..1000

Formula

A(x) = Sum_{k>=0} a(k) * x^k = Product_{k>=0} (1+3*x^(k+1))^a(k).

a(0) = 1; a(n) = (-1/n) * Sum_{k=1..n} ( Sum_{d|k} d * (-3)^(k/d) * a(d-1) ) * a(n-k).

Prog

(PARI) seq(n) = my(A=1); for(i=1, n, A=exp(sum(k=1, i, (-1)^(k+1)*subst(A, x, x^k)*(3*x)^k/k)+x*O(x^n))); Vec(A);

Crossrefs

Cf. A004111, A363441, A363443.

Cf. A363426, A363439.

Sequence in context: A175596 A261397 A238906 * A212418 A337039 A025226

Adjacent sequences: A363439 A363440 A363441 * A363443 A363444 A363445

Keyword

nonn

Author

Seiichi Manyama, Jun 02 2023

Status

approved