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A193459 Total number of distinct divisors of all numbers that can be written by rearranging the digits of n in decimal representation. 4

%I #11 Jan 29 2014 04:05:25

%S 1,2,2,3,2,4,2,4,3,4,2,8,3,5,6,6,3,8,5,6,8,4,7,12,8,6,13,8,7,8,3,7,4,

%T 5,5,12,3,5,6,8,5,12,5,6,11,9,5,16,6,6,6,8,5,11,4,11,8,7,5,12,6,6,12,

%U 9,11,8,7,8,14,8,3,13,3,5,8,7,4,10,3,10,8

%N Total number of distinct divisors of all numbers that can be written by rearranging the digits of n in decimal representation.

%C a(n) >= A000005(n), a(A193460(n)) = A000005(A193460(n)).

%H Reinhard Zumkeller, <a href="/A193459/b193459.txt">Table of n, a(n) for n = 1..10000</a>

%e a(20) = #{1,2,4,5,10,20} = 6;

%e a(21) = #{1,2,3,4,6,7,12,21} = 8;

%e a(22) = #{1,2,11,22} = 4;

%e a(23) = #{1,2,4,8,16,23,32} = 7;

%e a(24) = #{1,2,3,4,6,7,8,12,14,21,24,42} = 12;

%e a(25) = #{1,2,4,5,13,25,26,52} = 8;

%e a(26) = #{1,2,13,26,31,62} = 6;

%e a(27) = #{1,2,3,4,6,8,9,12,18,24,27,36,72} = 13;

%e a(28) = #{1,2,4,7,14,28,41,82} = 8;

%e a(29) = #{1,2,4,23,29,46,92} = 7.

%o (Haskell)

%o import Data.List (permutations, nub)

%o a193459 n =

%o length $ nub $ concatMap divisors $ map read $ permutations $ show n

%o where divisors n = filter ((== 0) . mod n) [1..n]

%o a193459_list = map a193459 [1..]

%Y Cf. A047726.

%K nonn,base,look

%O 1,2

%A _Reinhard Zumkeller_, Jul 26 2011

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