login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A062679 Numbers such that every divisor (except 1, but including the number itself) contains the digit 9. 3
19, 29, 59, 79, 89, 97, 109, 139, 149, 179, 191, 193, 197, 199, 229, 239, 269, 293, 349, 359, 379, 389, 397, 409, 419, 439, 449, 479, 491, 499, 509, 569, 593, 599, 619, 659, 691, 709, 719, 739, 769, 797, 809, 829, 839, 859, 907, 911, 919, 929, 937, 941, 947 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Different from A106093. 1691 = 19 * 89 is the smallest term that is not in A106093. - Franklin T. Adams-Watters, Apr 30 2007

LINKS

Table of n, a(n) for n=1..53.

EXAMPLE

7961 has divisors 19, 419 and 7961, all of which contain the digit 9.

MATHEMATICA

fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 1000], fQ[#, 9] &] (* Robert G. Wilson v, Jun 11 2014 *)

d9Q[n_]:=First[Union[DigitCount[#, 10, 9]&/@Rest[Divisors[n]]]]>0; Select[ Range[ 2, 1000], d9Q] (* Harvey P. Dale, Sep 12 2014 *)

PROG

(PARI) isok(n) = {if (n==1, return (0)); d = divisors(n); for (k=1, #d, if ((d[k] != 1) && (vecmax(digits(d[k])) != 9), return (0)); ); return (1); } \\ Michel Marcus, Nov 21 2015

(MAGMA) [n: n in [2..1000] | forall{Divisors(n)[i]: i in [2..NumberOfDivisors(n)] | 9 in Intseq(Divisors(n)[i])}]; // Bruno Berselli, Nov 21 2015

CROSSREFS

Sequence in context: A156782 A092600 A106124 * A106093 A084666 A242265

Adjacent sequences:  A062676 A062677 A062678 * A062680 A062681 A062682

KEYWORD

base,easy,nonn

AUTHOR

Erich Friedman, Jul 04 2001

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 17 00:03 EDT 2019. Contains 328103 sequences. (Running on oeis4.)