OFFSET
1,1
COMMENTS
All terms are even. - Robert Israel, Nov 23 2023
LINKS
Robert Israel, Table of n, a(n) for n = 1..1655
FORMULA
a(n) = [x^n] Sum_{k>0} (1/(1 - k*x^k)^(n+1) - 1).
MAPLE
f:= proc(n) local d;
add((n/d)^d * binomial(n+d, n), d = numtheory:-divisors(n))
end proc:
map(f, [$1..30]); # Robert Israel, Nov 23 2023
MATHEMATICA
a[n_] := DivisorSum[n, (n/#)^# * Binomial[# + n, n] &]; Array[a, 30] (* Amiram Eldar, Jul 05 2023 *)
PROG
(PARI) a(n) = sumdiv(n, d, (n/d)^d*binomial(d+n, n));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 14 2023
STATUS
approved