OFFSET
1,1
EXAMPLE
a(3)=1212 because the divisors of 1212 are [1, 2, 3, 4, 6, 12, 101, 202, 303, 404, 606, 1212] and 1+2+3+4+6+21+11+22+33+44+66+2211 = 2424 = 2*1212.
CROSSREFS
KEYWORD
base,more,nonn
AUTHOR
Jason Earls, Jun 11 2003
EXTENSIONS
98918163, 149308749, 250094358 from Sean A. Irvine, Nov 19 2009
STATUS
approved