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A242840
Number of compositions of n with difference -1 between the number of odd parts and the number of even parts, both counted without multiplicity.
2
1, 0, 2, 0, 2, 6, 15, 44, 74, 202, 351, 766, 1301, 2626, 4677, 8993, 16466, 31671, 60266, 116751, 229180, 452667, 905627, 1815394, 3673666, 7429123, 15109955, 30696510, 62512866, 127140993, 258745131, 525845884, 1068309682, 2167462318, 4393853912, 8896007640
OFFSET
2,3
LINKS
EXAMPLE
a(2) = 1: [2].
a(4) = 2: [2,2], [4].
a(6) = 2: [2,2,2], [6].
a(7) = 6: [1,2,4], [1,4,2], [2,1,4], [2,4,1], [4,1,2], [4,2,1].
a(8) = 15: [2,2,2,2], [1,1,2,4], [1,1,4,2], [1,2,1,4], [1,2,4,1], [1,4,1,2], [1,4,2,1], [2,1,1,4], [2,1,4,1], [2,4,1,1], [4,1,1,2], [4,1,2,1], [4,2,1,1], [4,4], [8].
CROSSREFS
Column k=-1 of A242626.
Sequence in context: A175802 A161803 A057980 * A081081 A111111 A185343
KEYWORD
nonn
AUTHOR
Alois P. Heinz, May 23 2014
STATUS
approved