OFFSET
0,4
COMMENTS
A strict composition of n (A032020) is a finite sequence of distinct positive integers summing to n.
Is there a simple generating function?
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: Sum_{k>=0} k! * [y^k](Product_{j>=1} 1 + y*x^j*A000009(j)). - Andrew Howroyd, Apr 16 2021
EXAMPLE
The a(1) = 1 through a(5) = 11 ways:
(1) (2) (3) (4) (5)
(2,1) (3,1) (3,2)
(1),(2) (1),(3) (4,1)
(2),(1) (3),(1) (1),(4)
(1),(2,1) (2),(3)
(2,1),(1) (3),(2)
(4),(1)
(1),(3,1)
(2,1),(2)
(2),(2,1)
(3,1),(1)
MATHEMATICA
strptn[n_]:=Select[IntegerPartitions[n], UnsameQ@@#&];
Table[Length[Join@@Table[Tuples[strptn/@ctn], {ctn, Join@@Permutations/@strptn[n]}]], {n, 0, 10}]
PROG
(PARI) \\ here Q(N) gives A000009 as a vector.
Q(n) = {Vec(eta(x^2 + O(x*x^n))/eta(x + O(x*x^n)))}
seq(n)={my(b=Q(n)); [subst(serlaplace(p), y, 1) | p<-Vec(prod(k=1, n, 1 + y*x^k*b[1+k] + O(x*x^n)))]} \\ Andrew Howroyd, Apr 16 2021
CROSSREFS
Multiset partitions of partitions are A001970.
Splittings of strict partitions are A072706.
Set partitions of strict partitions are A294617.
Splittings of partitions with distinct sums are A336131.
Cf. A008289, A011782, A304786, A318683, A318684, A319794, A323583, A336128, A336130, A336132, A336133.
Partitions:
- Partitions of each part of a partition are A063834.
- Compositions of each part of a partition are A075900.
- Strict partitions of each part of a partition are A270995.
- Strict compositions of each part of a partition are A336141.
Strict partitions:
- Partitions of each part of a strict partition are A271619.
- Compositions of each part of a strict partition are A304961.
- Strict partitions of each part of a strict partition are A279785.
- Strict compositions of each part of a strict partition are A336142.
Compositions:
- Partitions of each part of a composition are A055887.
- Compositions of each part of a composition are A133494.
- Strict partitions of each part of a composition are A304969.
- Strict compositions of each part of a composition are A307068.
Strict compositions:
- Partitions of each part of a strict composition are A336342.
- Compositions of each part of a strict composition are A336127.
- Strict partitions of each part of a strict composition are A336343.
- Strict compositions of each part of a strict composition are A336139.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jul 19 2020
STATUS
approved