A136904 Numbers k such that k and k^2 use only the digits 0, 2, 4, 6 and 8.

0, 2, 8, 20, 22, 68, 80, 200, 202, 220, 262, 668, 680, 800, 2000, 2002, 2020, 2022, 2200, 2202, 2620, 6668, 6680, 6800, 8000, 8262, 20000, 20002, 20020, 20022, 20200, 20220, 20602, 22000, 22002, 22020, 24622, 26200, 66668, 66680, 66800, 68000, 80000, 82620, 200000, 200002, 200020, 200022, 200200, 200202, 200220, 202000, 202002, 202200, 206020

Offset: 1

Author

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

Keywords

• base
• nonn

Comments

Generated with DrScheme.

Subsequence of A014263. - Michel Marcus, Oct 04 2013

Examples

			828268460602^2 = 686028642828006826202404.
		

Links

• Jonathan Wellons, Table of n, a(n) for n = 1..1038
• J. Wellons, Tables of Shared Digits [archived]

Crossrefs

Cf. A014263.

Programs

Mathematica

Select[Range[0,206050],AllTrue[Join[IntegerDigits[#],IntegerDigits[#^2]],EvenQ] &] (* Stefano Spezia, Jul 03 2025 *)

PARI

evdigs(n) = {if (n==0, return (1)); digs = digits(n); for (i = 1, #digs, if (digs[i] % 2, return (0));); return (1);}
isok(n) = evdigs(n) && evdigs(n^2); \\ Michel Marcus, Oct 04 2013