A371320 E.g.f. satisfies A(x) = exp(x) + x^2*A(x)^3.

1, 1, 3, 19, 181, 2341, 38071, 748567, 17262505, 457068745, 13667029291, 455560747291, 16750696633309, 673549397276653, 29403437531813983, 1384945157486054431, 70010050730247746641, 3780682522365453684625, 217218502250130209410387

Offset

0,3

Links

Table of n, a(n) for n=0..18.

Formula

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

Prog

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

Crossrefs

Cf. A087208, A371319.

Sequence in context: A303064 A343672 A161630 * A121083 A343685 A213533

Adjacent sequences: A371317 A371318 A371319 * A371321 A371322 A371323

Keyword

nonn

Author

Seiichi Manyama, Mar 18 2024

Status

approved