OFFSET
1,4
LINKS
Robert Israel, Table of n, a(n) for n = 1..450
FORMULA
L.g.f.: log(Product_{n>=1} (1 + x^n)^a(n)) = Sum_{n>=1} a(n+1)*x^n/n.
MAPLE
f:= proc(n) option remember;
add((-1)^((n-1)/d+1)*d*procname(d), d = numtheory:-divisors(n-1))
end proc:
f(1):= 1:
map(f, [$1..30]); # Robert Israel, Aug 30 2018
MATHEMATICA
a[1] = 1; a[n_] := a[n] = Sum[(-1)^((n - 1)/d + 1) d a[d] , {d, Divisors[n - 1]}]; Table[a[n], {n, 24}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Aug 29 2018
STATUS
approved