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

1,1

Links

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

Example

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

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 *)

Prog

(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

Crossrefs

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

Sequence in context: A088845 A013685 A108157 * A097785 A145922 A145981

Adjacent sequences: A062673 A062674 A062675 * A062677 A062678 A062679

Keyword

base,easy,nonn

Author

Erich Friedman, Jul 04 2001

Extensions

Offset corrected by Amiram Eldar, Nov 07 2019

Status

approved