A242839 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, 0, 5, 0, 14, 0, 22, 24, 104, 228, 518, 1272, 2621, 5986, 11836, 25396, 49077, 100200, 192678, 381724, 730806, 1424956, 2727666, 5271456, 10111091, 19503830, 37551786, 72600610, 140531739, 273027876, 531953163, 1040051736, 2040532257, 4017104634, 7935847124

Offset

6,1

Links

Alois P. Heinz, Table of n, a(n) for n = 6..500

Example

a(6) = 2: [2,4], [4,2].
a(8) = 5: [2,2,4], [2,4,2], [4,2,2], [2,6], [6,2].
a(13) = 24 = 4!: all permutations of {1,2,4,6}.

Crossrefs

Column k=-2 of A242626.

Sequence in context: A281731 A361921 A245928 * A105523 A210628 A090192

Adjacent sequences: A242836 A242837 A242838 * A242840 A242841 A242842

Keyword

nonn

Author

Alois P. Heinz, May 23 2014

Status

approved