A242842 Number of compositions of n with difference 2 between the number of odd parts and the number of even parts, both counted without multiplicity.

2, 3, 6, 11, 20, 25, 41, 85, 148, 355, 751, 1701, 3756, 8255, 17513, 37038, 76349, 156618, 317591, 639142, 1279302, 2546711, 5057675, 10010975, 19788607, 39058684, 77055159, 151930328, 299600229, 590849561, 1165782514, 2301229945, 4545782370, 8985884632

Offset

4,1

Links

Alois P. Heinz, Table of n, a(n) for n = 4..500

Example

a(4) = 2: [1,3], [3,1].
a(5) = 3: [1,1,3], [1,3,1], [3,1,1].
a(6) = 6: [1,1,1,3], [1,1,3,1], [1,3,1,1], [3,1,1,1], [1,5], [5,1].

Crossrefs

Column k=2 of A242626.

Sequence in context: A238644 A191629 A285553 * A327665 A131269 A358027

Adjacent sequences: A242839 A242840 A242841 * A242843 A242844 A242845

Keyword

nonn

Author

Alois P. Heinz, May 23 2014

Status

approved