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 A062680 Composite numbers n such that every divisor (except 1) of n contains the digit 9. 2
 1691, 2291, 3629, 5191, 5539, 5597, 6931, 7391, 7921, 7961, 8497, 8791, 9101, 9329, 9409, 9481, 9671, 9701, 10981, 10991, 11269, 13129, 13891, 14239, 15089, 15931, 15941, 16999, 17197, 17309, 17879, 17951, 17993, 18091, 18449, 18829, 18943 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE 7961 has divisors 19, 419 and 7961, all of which contain the digit 9 MATHEMATICA fQ[n_] := Union[Drop[Last /@ Sort /@ IntegerDigits[ Divisors[ n]], 1]] == {9}; Select[ Range[ 19110], fQ[ # ] == True && ! PrimeQ[ # ] &] (* Zak Seidov and Robert G. Wilson v, May 17 2005 *) fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 19110], !PrimeQ[#] && fQ[#, 9] &] (* Robert G. Wilson v, Jun 11 2014 *) CROSSREFS Composite members of A062679. Sequence in context: A020241 A065903 A204488 * A251291 A120564 A237533 Adjacent sequences:  A062677 A062678 A062679 * A062681 A062682 A062683 KEYWORD base,easy,nonn AUTHOR Erich Friedman, Jul 04 2001 EXTENSIONS Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, May 16 2007 STATUS approved

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Last modified September 18 20:22 EDT 2019. Contains 327181 sequences. (Running on oeis4.)