login
Numbers k such that k and k^2 use only the digits 1, 3, 8 and 9.
0

%I #11 May 10 2024 10:59:21

%S 1,3,9,1998333891

%N Numbers k such that k and k^2 use only the digits 1, 3, 8 and 9.

%C Generated with DrScheme.

%H Jonathan Wellons, <a href="https://web.archive.org/web/20090206165028/http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a> [archived]

%e 1998333891^2 = 3993338339919199881.

%t With[{c={1,3,8,9}},Select[Flatten[Table[FromDigits/@Tuples[c,n],{n,10}]], SubsetQ[c,IntegerDigits[#^2]]&]] (* _Harvey P. Dale_, Dec 04 2018 *)

%K base,nonn,more

%O 1,2

%A Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008