A062676 Composite and every divisor (except 1) contains the digit 7.

497, 679, 749, 799, 1207, 1379, 1739, 1799, 1897, 2479, 2627, 2701, 2779, 3337, 3713, 3997, 4607, 4709, 4711, 4739, 4757, 4907, 5173, 5257, 5327, 5579, 5729, 5767, 5789, 6179, 6749, 6769, 6797, 6887, 6979, 7081, 7169, 7289, 7379, 7597, 7609, 7663

Offset: 1

Author

Erich Friedman, Jul 04 2001

Keywords

• base
• easy
• nonn

Examples

			799 has divisors 17, 47 and 799, all of which contain the digit 7.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A062653, A062664, A062667, A062668, A062669, A062670, A062671, A062672, A062673, A062674, A062675, A062677, A062678, A062679, A062680.

Programs

Magma

[k:k in [2..8000]|  not IsPrime(k) and forall{d:d in Set(Divisors(k)) diff {1}| 7 in Intseq(d)}];// Marius A. Burtea, Nov 07 2019

Mathematica

fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 7670], !PrimeQ[#] && fQ[#, 7] &] (* Robert G. Wilson v, Jun 11 2014 *)

Extensions

Offset corrected by Amiram Eldar, Nov 07 2019