A077046 Doubly restricted composition numbers: number of compositions of [n^2/2] into exactly n positive integers each strictly less than n.

0, 1, 3, 19, 155, 1751, 24017, 398567, 7635987, 167729959, 4123838279, 112835748609, 3386455204288, 110976634957761, 3932912125462725, 150186639579545295, 6137695417757646851, 267654541150392845543, 12391407810082341898091, 607584722159224093306229

Offset

1,3

Links

Alois P. Heinz, Table of n, a(n) for n = 1..70

Index entries for sequences related to compositions

Formula

a(n) = A077042(n-1, n).

a(n) ~ exp(-1)*sqrt(6/Pi)*n^(n-3/2). - Vaclav Kotesovec, Mar 26 2016

Example

a(3) = 3 since the compositions of [3^2/2]=4 into exactly 3 positive integers each strictly less than 3 are: 1+1+2, 1+2+1 and 2+1+1.

Crossrefs

Cf. A077042, A077045, A077047, A077048.

Sequence in context: A235134 A235322 A105784 * A232607 A307697 A320352

Adjacent sequences: A077043 A077044 A077045 * A077047 A077048 A077049

Keyword

nonn

Author

Henry Bottomley, Oct 22 2002

Status

approved