OFFSET
1,1
EXAMPLE
Proper divisors of 30 are {1,2,3,5,6,10,15}: [3,10,1,6,5,2,15] -> (3+10,10+1,1+6,6+5,5+2,2+15) = (13,11,7,11,7,17): therefore 12 is a term.
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jun 18 2004
EXTENSIONS
More terms from Ryan Propper, Jul 22 2005
STATUS
approved