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A062653 Every divisor (except 1) contains the digit 2. 17
2, 23, 29, 127, 211, 223, 227, 229, 233, 239, 241, 251, 254, 257, 263, 269, 271, 277, 281, 283, 293, 421, 422, 482, 502, 521, 523, 526, 529, 542, 562, 727, 821, 823, 827, 829, 842, 929, 1021, 1042, 1123, 1129, 1201, 1213, 1217, 1223, 1229, 1231, 1237 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

254 has divisors 1, 2, 127 and 254, all of which contain the digit 2.

MATHEMATICA

fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 1300], fQ[#, 2] &]  (* Robert G. Wilson v, Jun 11 2014 *)

PROG

(MAGMA) [k:k in [2..1300]| forall{d:d in Set(Divisors(k)) diff {1}| 2 in Intseq(d)}]; // Marius A. Burtea, Nov 07 2019

(PARI) has2(n)=if(n==1, return(1)); !!setsearch(Set(digits(n)), 2)

is(n)=fordiv(n, d, if(!has2(d), return(0))); 1 \\ Charles R Greathouse IV, Jan 24 2020

CROSSREFS

Cf. A062664, A062667, A062668, A062669, A062670, A062671, A062672, A062673, A062674, A062675, A062676, A062677, A062678, A062679, A062680.

Sequence in context: A034843 A084373 A107148 * A208272 A306086 A045708

Adjacent sequences:  A062650 A062651 A062652 * A062654 A062655 A062656

KEYWORD

base,easy,nonn

AUTHOR

Erich Friedman, Jul 04 2001

EXTENSIONS

Offset corrected by Amiram Eldar, Nov 07 2019

STATUS

approved

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Last modified December 2 16:46 EST 2020. Contains 338877 sequences. (Running on oeis4.)