OFFSET
1,2
LINKS
EXAMPLE
a(5) = 12 since the divisors of 12 are 1,2,3,4,6 and 12 and the five distinct prime signatures arising are 1, p, p*q, p^2 and p^2*q.
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Jul 01 2003
EXTENSIONS
More terms from David Wasserman, Jan 25 2005
STATUS
approved