OFFSET
2,1
COMMENTS
There are d(n)*(d(n)-1)/2 sums of pairs of distinct positive divisors of n, where d(n) = number of positive divisors of n.
EXAMPLE
The positive divisors of 6 are 1,2,3,6. Letting d(m) = the number of positive divisors of m: d(1+2)=2; d(1+3)=3; d(1+6)=2; d(2+3)=2; d(2+6)=4; d(3+6)=3. The maximum of these values is 4, so a(6) = 4.
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jan 03 2008
EXTENSIONS
More terms from Sean A. Irvine, Feb 28 2011
STATUS
approved