A175507 Numbers such that each digit from 0 to 9 appears at least 7 times in the digits of their divisors.

7980, 8190, 9360, 10920, 11760, 11880, 12870, 13230, 13860, 14820, 15960, 16380, 16740, 17640, 17940, 18216, 18270, 18360, 18720, 18810, 18900, 19040, 19080, 19140, 19656, 19740, 20196, 20580, 20790, 20880, 21168, 21560, 21840, 22176

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Erich Friedman, What's Special About This Number? (See entry 7980.)

Example

5460 is not in the sequence because the divisors, 1, 2, 3, 4, 5, 6, 7, 10, 12, 13, 14, 15, 20, 21, 26, 28, 30, 35, 39, 42, 52, 60, 65, 70, 78, 84, 91, 105, 130, 140, 156, 182, 195, 210, 260, 273, 364, 390, 420, 455, 546, 780, 910, 1092, 1365, 1820, 2730, 5460, contain the digit 7 only 6 times (namely once in 7, 70, 78, 273, 780 and 2730), which is not enough.

Mathematica

fQ[n_] := Block[{s = Transpose@ Tally[ Sort[ Flatten[ IntegerDigits@# & /@ Divisors@ n]]]}, First@ s == {0, 1, 2, 3, 4, 5, 6, 7, 8, 9} && Min@ Last@ s > 6]; k = 1; lst = {}; While[k < 22319, If[ fQ@k, AppendTo[lst, k]]; k++ ]; lst (* Robert G. Wilson v, Jul 31 2010 *)

Crossrefs

Cf. A059436.

Sequence in context: A236786 A252190 A233730 * A126893 A217068 A043614

Adjacent sequences: A175504 A175505 A175506 * A175508 A175509 A175510

Keyword

base,nonn,easy

Author

R. J. Mathar, Jun 02 2010

Extensions

More terms from Robert G. Wilson v, Jul 31 2010

Status

approved