OFFSET
1,6
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = -Sum_{d|n, d > 1} mu(d) * A000009(n/d).
EXAMPLE
The a(18) = 10 strict partitions are (18), (10,8), (12,6), (14,4), (15,3), (16,2), (8,6,4), (9,6,3), (10,6,2), (12,4,2).
MAPLE
with(numtheory):
b:= proc(n) option remember; `if`(n=0, 1, add(add(
`if`(d::odd, d, 0), d=divisors(j))*b(n-j), j=1..n)/n)
end:
a:= n-> -add(mobius(d)*b(n/d), d=divisors(n) minus {1}):
seq(a(n), n=1..100); # Alois P. Heinz, Apr 23 2018
MATHEMATICA
Table[-Sum[MoebiusMu[d]*PartitionsQ[n/d], {d, Rest[Divisors[n]]}], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Apr 20 2018
STATUS
approved