A377888 E.g.f. A(x) satisfies A(x) = exp(x * A(x))/(1 - x*A(x)^2).

1, 2, 17, 289, 7541, 267041, 11974645, 650666731, 41560476809, 3052145052433, 253400719220801, 23470964805942083, 2399562226994185885, 268404500411311273465, 32606551238103342068717, 4275233840499570086190331, 601753408713140793660643985, 90500525005651471292191270433

Offset

0,2

Links

Table of n, a(n) for n=0..17.

Formula

a(n) = n! * Sum_{k=0..n} (2*n-k+1)^(k-1) * binomial(3*n-2*k,n-k)/k!.

Prog

(PARI) a(n) = n!*sum(k=0, n, (2*n-k+1)^(k-1)*binomial(3*n-2*k, n-k)/k!);

Crossrefs

Cf. A352410, A377831, A377889.

Cf. A371318.

Sequence in context: A380771 A380718 A078367 * A090306 A304857 A007785

Adjacent sequences: A377885 A377886 A377887 * A377889 A377890 A377891

Keyword

nonn

Author

Seiichi Manyama, Nov 10 2024

Status

approved