A174993 a(n) = -Floor[n/2]! + Sum[(Eulerian[n - j, j]), {j, 0, Floor[n/2]}]

0, 0, 1, 4, 11, 36, 119, 443, 1718, 7245, 32313, 153730, 771677, 4088053, 22741818, 132596893, 807840501, 5132194862, 33924901021, 232905225561, 1657803862422, 12215420390037, 93042805475305, 731622623516178, 5931914758691917, 49535825763153373, 425606813712984146, 3758735172560999933, 34089943206777076429, 317245175458777517030

Offset

1,4

Links

Table of n, a(n) for n=1..30.

Formula

a(n)=-Floor[n/2]! + Sum[(Eulerian[n - j, j]), {j, 0, Floor[n/2]}]=A000800(n)-Floor[(n-1)/2]!

Mathematica

<<Combinatorica`
a = Table[-Floor[n/2]! + Sum[(Eulerian[n - j, j]), {j, 0, Floor[n/2]}], {n, 1, 30}]

Crossrefs

Cf. A000800.

Sequence in context: A106640 A109268 A256960 * A149238 A149239 A149240

Adjacent sequences: A174990 A174991 A174992 * A174994 A174995 A174996

Keyword

nonn

Author

Roger L. Bagula, Dec 02 2010

Status

approved