A371139 E.g.f. satisfies A(x) = 1 + x^2*A(x)^2*(exp(x*A(x)) - 1).

1, 0, 0, 6, 12, 20, 2190, 17682, 94136, 4762872, 83210490, 920248670, 34266719652, 948535937076, 17568958623398, 607198057666410, 22018456385103600, 595499717140604912, 21682086461493768306, 926586132659265073590, 33197900968981072951580

Offset

0,4

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = (n!)^2 * Sum_{k=0..floor(n/3)} Stirling2(n-2*k,k)/( (n-2*k)! * (n-k+1)! ).

Prog

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

Crossrefs

Cf. A371119.

Sequence in context: A362892 A371304 A355508 * A371145 A370989 A055458

Adjacent sequences: A371136 A371137 A371138 * A371140 A371141 A371142

Keyword

nonn

Author

Seiichi Manyama, Mar 12 2024

Status

approved