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 A345390 Numbers whose set of divisors contains every digit at least twice. 2
 540, 720, 760, 810, 918, 1080, 1140, 1170, 1260, 1404, 1440, 1512, 1520, 1530, 1560, 1620, 1740, 1800, 1820, 1824, 1836, 1872, 1890, 1908, 1960, 2016, 2028, 2052, 2070, 2072, 2088, 2106, 2112, 2124, 2142, 2156, 2160, 2184, 2208, 2280, 2340, 2380, 2430, 2508, 2520 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Compare to A095050: Numbers such that all ten digits are needed to write all positive divisors in decimal representation. LINKS Michael S. Branicky, Table of n, a(n) for n = 1..10000 EXAMPLE The divisors of 918 are 1, 2, 3, 6, 9, 17, 18, 27, 34, 51, 54, 102, 153, 306, 459, and 918. Every digit appears at least twice. Thus, 918 is in this sequence. MAPLE q:= n-> (p-> is(min(seq(coeff(p, x, j), j=0..9))>1))(add(x^i, i= map(d-> convert(d, base, 10)[], [numtheory[divisors](n)[]]))): select(q, [\$10..2600])[]; # Alois P. Heinz, Apr 21 2022 MATHEMATICA Select[Range[3000], Length[Transpose[Tally[Flatten[IntegerDigits[Divisors[#]]]]][[2]]] == 10 && Min[Transpose[Tally[Flatten[IntegerDigits[Divisors[#]]]]][[2]]] > 1 &] PROG (Python) from sympy import divisors def ok(n): digits_used = {d:0 for d in "0123456789"} for div in divisors(n, generator=True): for d in str(div): digits_used[d] += 1 if all(digits_used[d] > 1 for d in "0123456789"): return True return False print([k for k in range(2521) if ok(k)]) # Michael S. Branicky, Jun 25 2022 CROSSREFS Cf. A059436, A095050. Sequence in context: A184546 A252386 A289221 * A261290 A253463 A255105 Adjacent sequences: A345387 A345388 A345389 * A345391 A345392 A345393 KEYWORD nonn,base AUTHOR Tanya Khovanova, Jun 17 2021 STATUS approved

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Last modified May 25 14:17 EDT 2024. Contains 372788 sequences. (Running on oeis4.)