OFFSET
1,2
COMMENTS
Moebius transform of A001764.
MATHEMATICA
Table[Sum[MoebiusMu[n/d] Binomial[3 d, d]/(2 d + 1), {d, Divisors[n]}], {n, 24}]
PROG
(PARI) a(n) = sumdiv(n, d, moebius(n/d)*binomial(3*d, d)/(2*d+1)); \\ Michel Marcus, Aug 07 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Aug 07 2021
STATUS
approved