OFFSET
1,2
COMMENTS
A primitive subset has no nonempty proper subset whose members sum to zero. Note that a(30) is the first term for which the formulas do not apply. For n=30, there are 1,0,15,10,0,5,30,60,60,30 primitive subsets of size 0,1,2,...,9.
FORMULA
For primes p and q, if n = p^i, then a(n)=1+n/p; if n=p^i q^j, then a(n)=1+n/p+n/q.
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, May 23 2005
STATUS
approved