A257221 Numbers that have at least one divisor containing the digit 4 in base 10.

4, 8, 12, 14, 16, 20, 24, 28, 32, 34, 36, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52, 54, 56, 60, 64, 68, 70, 72, 74, 76, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 108, 112, 114, 116, 120, 123, 124, 126, 128, 129, 132, 134, 135, 136, 138, 140, 141

Offset

1,1

Comments

Numbers k whose concatenation of divisors A037278(k), A176558(k), A243360(k) or A256824(k) contains a digit 4.

Sequences of numbers k whose concatenation of divisors contains a digit j in base 10 for 0 <= j <= 9: A209932 for j = 0, A000027 for j = 1, A257219 for j = 2, A257220 for j = 3, A257221 for j = 4, A257222 for j = 5, A257223 for j = 6, A257224 for j = 7, A257225 for j = 8, A257226 for j = 9.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Formula

a(n) ~ n. - Charles R Greathouse IV, Apr 30 2015

Example

16 is in sequence because the list of divisors of 16: (1, 2, 4, 8, 16) contains digit 4.

Mathematica

Select[Range@ 141, Part[Plus @@ DigitCount@ Divisors@ #, 4] > 0 &] (* Michael De Vlieger, Apr 20 2015 *)
Select[Range[200], Count[Flatten[IntegerDigits/@Divisors[#]], 4]>0&] (* Harvey P. Dale, May 05 2022 *)

Prog

(Magma) [n: n in [1..1000] | [4] subset Setseq(Set(Sort(&cat[Intseq(d): d in Divisors(n)])))]
(PARI) is(n)=fordiv(n, d, if(setsearch(Set(digits(d)), 4), return(1))); 0 \\ Charles R Greathouse IV, Apr 30 2015

Crossrefs

Cf. A037278, A176558, A243360, A256824.

Sequence in context: A311078 A328303 A311079 * A092453 A285374 A132457

Adjacent sequences: A257218 A257219 A257220 * A257222 A257223 A257224

Keyword

nonn,base

Author

Jaroslav Krizek, Apr 20 2015

Status

approved