|
| |
|
|
A345390
|
|
Numbers such that their set of divisors contains every digit at least twice.
|
|
1
|
|
|
|
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
|
Table of n, a(n) for n=1..45.
|
|
|
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 &]
|
|
|
CROSSREFS
|
Cf. 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
|
| |
|
|
