A345919 Numbers k such that the k-th composition in standard order (row k of A066099) has alternating sum < 0.
6, 12, 20, 24, 25, 27, 30, 40, 48, 49, 51, 54, 60, 72, 80, 81, 83, 86, 92, 96, 97, 98, 99, 101, 102, 103, 106, 108, 109, 111, 116, 120, 121, 123, 126, 144, 160, 161, 163, 166, 172, 184, 192, 193, 194, 195, 197, 198, 199, 202, 204, 205, 207, 212, 216, 217, 219
Offset: 1
Keywords
Examples
The initial terms and the corresponding compositions: 6: (1,2) 81: (2,4,1) 12: (1,3) 83: (2,3,1,1) 20: (2,3) 86: (2,2,1,2) 24: (1,4) 92: (2,1,1,3) 25: (1,3,1) 96: (1,6) 27: (1,2,1,1) 97: (1,5,1) 30: (1,1,1,2) 98: (1,4,2) 40: (2,4) 99: (1,4,1,1) 48: (1,5) 101: (1,3,2,1) 49: (1,4,1) 102: (1,3,1,2) 51: (1,3,1,1) 103: (1,3,1,1,1) 54: (1,2,1,2) 106: (1,2,2,2) 60: (1,1,1,3) 108: (1,2,1,3) 72: (3,4) 109: (1,2,1,2,1) 80: (2,5) 111: (1,2,1,1,1,1)
Crossrefs
The version for Heinz numbers of partitions is A119899.
These are the positions of terms < 0 in A124754.
The complement is A345913.
The weak (k <= 0) version is A345915.
The opposite (k < 0) version is A345917.
The version for reversed alternating sum is A345920.
A011782 counts compositions.
A097805 counts compositions by alternating (or reverse-alternating) sum.
A236913 counts partitions of 2n with reverse-alternating sum <= 0.
A345197 counts compositions by sum, length, and alternating sum.
Compositions of n, 2n, or 2n+1 with alternating/reverse-alternating sum k:
Programs
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Mathematica
stc[n_]:=Differences[Prepend[Join@@Position[Reverse[IntegerDigits[n,2]],1],0]]//Reverse; ats[y_]:=Sum[(-1)^(i-1)*y[[i]],{i,Length[y]}]; Select[Range[0,100],ats[stc[#]]<0&]
Comments