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 A257221 Numbers n that have at least one divisor containing the digit 4 in base 10. 8
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers n whose concatenation of divisors A037278(n), A176558(n), A243360(n) or A256824(n) contains a digit 4. Sequences of numbers n whose concatenation of divisors contains a digit k in base 10 for 0 <= k <= 9: A209932 for k = 0, A000027 for k = 1, A257219 for k = 2, A257220 for k = 3, A257221 for k = 4, A257222 for k = 5, A257223 for k = 6, A257224 for k = 7, A257225 for k = 8, A257226 for k = 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 *) 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

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Last modified October 15 04:33 EDT 2019. Contains 328026 sequences. (Running on oeis4.)