OFFSET
1,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
EXAMPLE
a(20) = #{1,2,4,5,10,20} = 6;
a(21) = #{1,2,3,4,6,7,12,21} = 8;
a(22) = #{1,2,11,22} = 4;
a(23) = #{1,2,4,8,16,23,32} = 7;
a(24) = #{1,2,3,4,6,7,8,12,14,21,24,42} = 12;
a(25) = #{1,2,4,5,13,25,26,52} = 8;
a(26) = #{1,2,13,26,31,62} = 6;
a(27) = #{1,2,3,4,6,8,9,12,18,24,27,36,72} = 13;
a(28) = #{1,2,4,7,14,28,41,82} = 8;
a(29) = #{1,2,4,23,29,46,92} = 7.
PROG
(Haskell)
import Data.List (permutations, nub)
a193459 n =
length $ nub $ concatMap divisors $ map read $ permutations $ show n
where divisors n = filter ((== 0) . mod n) [1..n]
a193459_list = map a193459 [1..]
CROSSREFS
KEYWORD
AUTHOR
Reinhard Zumkeller, Jul 26 2011
STATUS
approved