OFFSET
0,5
LINKS
FORMULA
a(n) = [x^n] 1 / (1 - Sum_{k: gcd(n,k) > 1} x^k).
EXAMPLE
a(9) = 4 because we have [9], [6, 3], [3, 6] and [3, 3, 3].
MAPLE
a:= proc(m) option remember; local b; b:=
proc(n) option remember; `if`(n=0, 1,
add(`if`(igcd(j, m)>1, b(n-j), 0), j=1..n))
end; forget(b); b(m$2)
end:
seq(a(n), n=0..82); # Alois P. Heinz, Jan 30 2020
MATHEMATICA
Table[SeriesCoefficient[1/(1 - Sum[Boole[GCD[k, n] > 1] x^k, {k, 1, n}]), {x, 0, n}], {n, 0, 51}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jan 30 2020
STATUS
approved