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

%I #9 Jul 05 2021 09:05:37

%S 0,2,8,20,22,68,80,200,202,220,262,668,680,800,2000,2002,2020,2022,

%T 2200,2202,2620,6668,6680,6800,8000,8262,20000,20002,20020,20022,

%U 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

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

%C Generated with DrScheme.

%C Subsequence of A014263. - _Michel Marcus_, Oct 04 2013

%H Jonathan Wellons, <a href="/A136904/b136904.txt">Table of n, a(n) for n = 1..1038</a>

%H J. Wellons, <a href="http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a>

%e 828268460602^2 = 686028642828006826202404.

%o (PARI) evdigs(n) = {if (n==0, return (1)); digs = digits(n); for (i = 1, #digs, if (digs[i] % 2, return (0));); return (1);}

%o isok(n) = evdigs(n) && evdigs(n^2); \\ _Michel Marcus_, Oct 04 2013

%K base,nonn

%O 1,2

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

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Last modified February 26 19:43 EST 2024. Contains 370352 sequences. (Running on oeis4.)