A241721 Number of compositions of n into distinct parts with exactly two descents.

1, 1, 2, 3, 15, 16, 29, 41, 65, 144, 179, 269, 382, 549, 739, 1286, 1564, 2254, 2978, 4124, 5304, 7264, 10157, 12941, 17027, 22194, 28663, 36884, 47306, 59837, 79467, 98114, 125117, 156392, 198113, 244710, 307908, 378429, 471337, 588642, 721300, 884498

Offset: 6

Author

Alois P. Heinz, Apr 27 2014

Keywords

• nonn

Examples

			a(9) = 3: [6,2,1], [5,3,1], [4,3,2].
a(10) = 15: [5,4,1], [7,2,1], [6,3,1], [5,3,2], [4,1,3,2], [2,1,4,3], [4,3,1,2], [4,2,3,1], [2,4,3,1], [1,4,3,2], [3,1,4,2], [3,2,4,1], [3,4,2,1], [4,2,1,3], [3,2,1,4].
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 6..1000

Crossrefs

Column k=2 of A241719.