OFFSET
1,1
COMMENTS
Since 1 is always a divisor of n, this is a subsequence of A011531. - Michel Marcus, Feb 12 2014
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
EXAMPLE
125 is in the sequence because the proper divisors of 125 are {1, 5, 25} with the same digits as 125.
MATHEMATICA
Pn[n_]:=Sort[DeleteDuplicates[Flatten[IntegerDigits[Take[Divisors[n], DivisorSigma[0, n]-1]]]]]; Fn[n_]:=Sort[DeleteDuplicates[IntegerDigits[n]]]; lst={}; Do[If[!PrimeQ[n]&&Pn[n]===Fn[n], AppendTo[lst, n]], {n, 2, 10^5}]; lst
Select[Range[10^5], ! PrimeQ@# && Union@ IntegerDigits@ # == Union @@ IntegerDigits /@ Most@ Divisors@ # &] (* Giovanni Resta, Feb 12 2014 *)
PROG
(PARI) isok(n) = { my(digs = []); fordiv(n, d, if (d != n, digs = concat(digs, digits(d)))); (n != 1) && !isprime(n) && vecsort(digs, , 8) == vecsort(digits(n), , 8); } \\ Michel Marcus, Feb 12 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Lagneau, Feb 12 2014
STATUS
approved