OFFSET
1,45
LINKS
EXAMPLE
1 = 1/2+1/4+1/9+1/12+1/18 = 1/2+1/5+1/6+1/12+1/20. The sum of the denominators of each of these is 45, these are the only 2 with sum of denominators = 45, so a(45)=2.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jud McCranie, Dec 16 1999
EXTENSIONS
R. L. Graham showed that a(n)>0 for n>77.
STATUS
approved