OFFSET
1,4
FORMULA
a(n) = Sum_{d|n} binomial(d+n/d-3,d) for n > 1.
If p is prime, a(p) = p - 2.
PROG
(PARI) a(n) = if(n<2, 0, sumdiv(n, d, binomial(d+n/d-3, d)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 30 2023
STATUS
approved