A358613 a(n) = Sum_{k=0..floor(n/3)} (-1)^k * (n-k)!/(k! * (n-3*k)!).

1, 1, 1, -1, -5, -11, -7, 31, 139, 245, -71, -1937, -5989, -6251, 25945, 144479, 304843, -177899, -3517351, -11743505, -10097381, 81902453, 433558201, 840235039, -1481279605, -15839941451, -48073840007, -8454966289, 564429256219, 2518098130645, 3490609807769

Offset

0,5

Links

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

Formula

a(n) = (4 * a(n-1) - a(n-2) - 2 * (2*n-3) * a(n-3))/3 for n > 2.

Prog

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

Crossrefs

Cf. A247917, A358560.

Sequence in context: A068419 A226586 A368055 * A329005 A290195 A082952

Adjacent sequences: A358610 A358611 A358612 * A358614 A358615 A358616

Keyword

sign

Author

Seiichi Manyama, Nov 23 2022

Status

approved