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A330898 Positive numbers k of the form x*y where k, x and y have the same set of decimal digits. 2
1, 11, 100, 111, 1000, 1010, 1100, 1111, 10000, 10010, 10100, 10110, 11000, 11010, 11100, 11110, 11111, 31003, 99190, 100000, 100010, 100100, 100110, 101000, 101010, 101100, 101101, 101110, 110000, 110010, 110100, 110110, 111000, 111010, 111100, 111111, 266616 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
If k belongs to the sequence, then 100*k also belongs to the sequence.
The positive repunits belong to the sequence.
The first pandigital term is 1047463798950190521 = 1023456789^2.
LINKS
EXAMPLE
The first terms, alongside an appropriate factorization and the corresponding set of digits, are:
n a(n) x y digits(n)
-- ------ --- ------ ---------
1 1 1 1 {1}
2 11 1 11 {1}
3 100 10 10 {0, 1}
4 111 1 111 {1}
5 1000 10 100 {0, 1}
6 1010 10 101 {0, 1}
7 1100 10 110 {0, 1}
8 1111 1 1111 {1}
9 10000 10 1000 {0, 1}
10 10010 10 1001 {0, 1}
11 10100 10 1010 {0, 1}
12 10110 10 1011 {0, 1}
13 11000 10 1100 {0, 1}
14 11010 10 1101 {0, 1}
15 11100 10 1110 {0, 1}
16 11110 101 110 {0, 1}
17 11111 1 11111 {1}
18 31003 103 301 {0, 1, 3}
19 99190 109 910 {0, 1, 9}
PROG
(PARI) is(n) = { my (s=Set(digits(n))); fordiv (n, d, if (Set(digits(d))==s && Set(digits(n/d))==s, return (1))); return (0) }
CROSSREFS
Sequence in context: A066329 A309870 A219896 * A287739 A287750 A287491
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, May 01 2020
STATUS
approved

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Last modified March 28 16:58 EDT 2024. Contains 371254 sequences. (Running on oeis4.)