login
A062668
Composite and every divisor (except 1) contains the digit 3.
17
39, 93, 309, 339, 393, 403, 713, 933, 939, 993, 1137, 1293, 1317, 1329, 1333, 1339, 1369, 1389, 1643, 1703, 1839, 1893, 2263, 2319, 2369, 2573, 3013, 3029, 3039, 3071, 3093, 3099, 3107, 3117, 3139, 3151, 3189, 3193, 3197, 3279, 3309, 3369, 3419, 3459
OFFSET
1,1
LINKS
EXAMPLE
93 has divisors 1, 3, 31 and 93, all of which contain the digit 3.
MATHEMATICA
fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 3460], !PrimeQ[#] && fQ[#, 3] &] (* Robert G. Wilson v, Jun 11 2014 *)
PROG
(Magma) [k:k in [2..3500]| forall{d:d in Set(Divisors(k)) diff {1}| 3 in Intseq(d)}]; // Marius A. Burtea, Nov 07 2019
KEYWORD
base,easy,nonn
AUTHOR
Erich Friedman, Jul 04 2001
EXTENSIONS
Offset corrected by Amiram Eldar, Nov 07 2019
STATUS
approved