OFFSET
1,1
EXAMPLE
Take 60, having sum of prime factors 2+2+3+5=12 and add that 12 to 60 to get 72, having the sum of its prime factors 2+2+2+3+3=12. We see that this 12 divides both 60 and 72.
For 2408, the sum of prime factors is 2+2+2+7+43=56, added to 2408 gives 2464, with sum of prime factors being 2+2+2+2+2+7+11=28; this 28 divides both 2408 and 2464.
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot, Aug 27 2007
EXTENSIONS
Edited by Olivier Gérard, Sep 27 2007
STATUS
approved