OFFSET
1,4
EXAMPLE
n=10: mu(3+10)=mu(3)=-1, mu(7+10)=mu(7)=-1, mu(8+10)=mu(8)=0 and mu(k+10)<>mu(k) for k in {1,2,4,5,6,8,9}, therefore a(10)=3.
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 12 2003
STATUS
approved