A136986 - OEIS

%I #14 Apr 16 2024 13:55:46

%S 1,2,11,12,21

%N Numbers k such that k and k^2 use only the digits 1, 2 and 4.

%C Sequence terminates.

%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 21^2 = 441.

%t Table[Select[(FromDigits/@Tuples[{1,2,4},d]),SubsetQ[{1,2,4},IntegerDigits[ #^2]]&],{d,2}]//Flatten (* _Harvey P. Dale_, Jan 10 2022 *)

%Y Cf. A137002.

%K base,fini,full,nonn

%O 1,2

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