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A175507
Numbers such that each digit from 0 to 9 appears at least 7 times in the digits of their divisors.
1
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
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
KEYWORD
base,nonn,easy
AUTHOR
R. J. Mathar, Jun 02 2010
EXTENSIONS
More terms from Robert G. Wilson v, Jul 31 2010
STATUS
approved