A363626 Number of integer compositions of n with weighted alternating sum 0.
1, 0, 0, 1, 1, 0, 2, 5, 7, 8, 14, 38, 64, 87, 174, 373, 649, 1069, 2051, 4091, 7453, 13276, 25260, 48990, 91378, 168890, 321661, 618323, 1169126, 2203649, 4211163, 8085240, 15421171, 29390131, 56382040, 108443047, 208077560, 399310778
Offset: 0
Keywords
Examples
The a(3) = 1 through a(10) = 14 compositions: (21) (121) . (42) (331) (242) (63) (541) (3111) (1132) (1331) (153) (2143) (2221) (11132) (4122) (3232) (21121) (12221) (5211) (4321) (112111) (23111) (13122) (15112) (121121) (14211) (31231) (1112111) (411111) (42121) (1311111) (114112) (212122) (213211) (311221) (322111) (3111121) (21211111)
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..150 (first 51 terms from Max Alekseyev)
Crossrefs
A000041 counts integer partitions.
Programs
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Mathematica
altwtsum[y_]:=Sum[(-1)^(k-1)*k*y[[k]],{k,1,Length[y]}]; Table[Length[Select[Join@@Permutations/@IntegerPartitions[n],altwtsum[#]==0&]],{n,0,10}]
Extensions
Terms a(22) onward from Max Alekseyev, Sep 05 2023
Comments