OFFSET
1,2
PROG
(PARI) a(n) = sumdiv(n, d, moebius(n/d)*binomial(2*d, d)^3)/(8*n) \\ Michel Marcus, Jun 15 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Lionel Levine (levine(AT)ultranet.com)
EXTENSIONS
More terms from Erich Friedman
STATUS
approved