OFFSET
0,5
COMMENTS
A composition of n is a finite sequence of positive integers with sum n.
EXAMPLE
The a(1) = 1 through a(9) = 10 compositions:
(1) (2) (3) (4) (5) (6) (7) (8) (9)
(1,1,2) (1,1,3) (1,1,4) (1,1,5) (1,1,6) (1,1,7)
(1,2,1) (1,2,2) (1,4,1) (1,3,3) (1,6,1) (1,4,4)
(2,1,1) (1,3,1) (4,1,1) (1,5,1) (2,2,4) (1,7,1)
(2,1,2) (2,2,3) (2,3,3) (2,2,5)
(2,2,1) (2,3,2) (2,4,2) (2,5,2)
(3,1,1) (3,1,3) (3,2,3) (4,1,4)
(3,2,2) (3,3,2) (4,4,1)
(3,3,1) (4,2,2) (5,2,2)
(5,1,1) (6,1,1) (7,1,1)
MATHEMATICA
Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], Range[Length[Union[#]]]==Sort[Length/@Split[Sort[#]]]&]], {n, 0, 10}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 21 2019
EXTENSIONS
a(21)-a(40) from Alois P. Heinz, Nov 21 2019
STATUS
approved