cp's OEIS Frontend

A330898 Positive numbers k of the form x*y where k, x and y have the same set of decimal digits.

%I A330898 #12 May 03 2020 13:43:53
%S A330898 1,11,100,111,1000,1010,1100,1111,10000,10010,10100,10110,11000,11010,
%T A330898 11100,11110,11111,31003,99190,100000,100010,100100,100110,101000,
%U A330898 101010,101100,101101,101110,110000,110010,110100,110110,111000,111010,111100,111111,266616
%N A330898 Positive numbers k of the form x*y where k, x and y have the same set of decimal digits.
%C A330898 If k belongs to the sequence, then 100*k also belongs to the sequence.
%C A330898 The positive repunits belong to the sequence.
%C A330898 The first pandigital term is 1047463798950190521 = 1023456789^2.
%H A330898 Rémy Sigrist, <a href="/A330898/b330898.txt">Table of n, a(n) for n = 1..10000</a>
%e A330898 The first terms, alongside an appropriate factorization and the corresponding set of digits, are:
%e A330898   n   a(n)    x    y       digits(n)
%e A330898   --  ------  ---  ------  ---------
%e A330898    1       1    1       1  {1}
%e A330898    2      11    1      11  {1}
%e A330898    3     100   10      10  {0, 1}
%e A330898    4     111    1     111  {1}
%e A330898    5    1000   10     100  {0, 1}
%e A330898    6    1010   10     101  {0, 1}
%e A330898    7    1100   10     110  {0, 1}
%e A330898    8    1111    1    1111  {1}
%e A330898    9   10000   10    1000  {0, 1}
%e A330898   10   10010   10    1001  {0, 1}
%e A330898   11   10100   10    1010  {0, 1}
%e A330898   12   10110   10    1011  {0, 1}
%e A330898   13   11000   10    1100  {0, 1}
%e A330898   14   11010   10    1101  {0, 1}
%e A330898   15   11100   10    1110  {0, 1}
%e A330898   16   11110  101     110  {0, 1}
%e A330898   17   11111    1   11111  {1}
%e A330898   18   31003  103     301  {0, 1, 3}
%e A330898   19   99190  109     910  {0, 1, 9}
%o A330898 (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) }
%Y A330898 Cf. A002275, A086066.
%K A330898 nonn,base
%O A330898 1,2
%A A330898 _Rémy Sigrist_, May 01 2020