OFFSET
1,2
LINKS
R. Zumkeller, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Divisor Function
EXAMPLE
n = 216 = 2*10^2 + 1*10^1 + 6*10^0: let D(n) = set of divisors of
n,
D(216)={1,2,3,4,6,8,9,12,18,24,27,36,54,72,108,216},
D(200)={1,2,4,5,8,10,20,25,40,50,100,200}, D(10)={1,2,5,10}, D(6)={1,2,3,6},
a(216) = #{1,2,3,4,6,8} = 6.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Mar 26 2008
STATUS
approved