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

Author

Henry Bottomley, Oct 22 2002

Keywords

• nonn

Examples

			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.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..70
• Index entries for sequences related to compositions

Crossrefs

Cf. A077042, A077045, A077047, A077048.

Formula

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

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