OFFSET
1,1
COMMENTS
First differs from A345168 in lacking 37, corresponding to the composition (3,2,1).
A composition of n is a finite sequence of positive integers summing to n. The k-th composition in standard order (row k of A066099) is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again.
EXAMPLE
The terms and corresponding standard compositions begin:
3: (1,1) 35: (4,1,1) 61: (1,1,1,2,1)
7: (1,1,1) 36: (3,3) 62: (1,1,1,1,2)
10: (2,2) 39: (3,1,1,1) 63: (1,1,1,1,1,1)
11: (2,1,1) 42: (2,2,2) 67: (5,1,1)
14: (1,1,2) 43: (2,2,1,1) 71: (4,1,1,1)
15: (1,1,1,1) 46: (2,1,1,2) 73: (3,3,1)
19: (3,1,1) 47: (2,1,1,1,1) 74: (3,2,2)
21: (2,2,1) 51: (1,3,1,1) 75: (3,2,1,1)
23: (2,1,1,1) 53: (1,2,2,1) 78: (3,1,1,2)
26: (1,2,2) 55: (1,2,1,1,1) 79: (3,1,1,1,1)
27: (1,2,1,1) 56: (1,1,4) 83: (2,3,1,1)
28: (1,1,3) 57: (1,1,3,1) 84: (2,2,3)
29: (1,1,2,1) 58: (1,1,2,2) 85: (2,2,2,1)
30: (1,1,1,2) 59: (1,1,2,1,1) 86: (2,2,1,2)
31: (1,1,1,1,1) 60: (1,1,1,3) 87: (2,2,1,1,1)
MATHEMATICA
stc[n_]:=Differences[Prepend[Join@@Position[Reverse[IntegerDigits[n, 2]], 1], 0]]//Reverse;
Select[Range[100], MatchQ[stc[#], {___, x_, x_, ___}]&]
CROSSREFS
Counting these compositions by sum and length gives A131044.
These compositions are counted by A261983.
A238279 counts compositions by sum and number of maximal runs.
A274174 counts compositions with equal parts contiguous.
A336107 counts non-anti-run permutations of prime factors.
For compositions in standard order (rows of A066099):
- Length is A000120.
- Sum is A070939
- Maximal runs are counted by A124767.
- Strict compositions are ranked by A233564.
- Maximal anti-runs are counted by A333381.
- Runs-resistance is A333628.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 03 2021
STATUS
approved