STATUS
reviewed
approved
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Revision History for A091853
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a(n) is the number of numbers k such that k is obtained by permuting the digits of n and gcd(n,k) > 1.
(history; published version)
(history; published version)
STATUS
proposed
reviewed
STATUS
editing
proposed
MATHEMATICA
Table[Count[Union@ Map[# Boole[! CoprimeQ[#, n]] &@ FromDigits@ # &, Permutations@ IntegerDigits@ n], _?(# > 0 &)], {n, 105}] (* Michael De Vlieger, Dec 16 2017 *)
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proposed
editing
STATUS
editing
proposed
COMMENTS
For a number like 12345 which is a multiple of three and does not contain zero, all 5! = 120 permutations yield a distinct number divisible by 3, thus a(12345) = 120. However, 120 occurs for the first time at n = 10236, which is also a multiple of three. - Antti Karttunen, Dec 16 2017
STATUS
proposed
editing
STATUS
editing
proposed
NAME
a(n) = is the number of numbers k such that k is obtained by permuting the digits of n and gcd(n,k) > 1.
STATUS
reviewed
editing
STATUS
proposed
reviewed
STATUS
editing
proposed