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 A137103 Numbers k such that k and k^2 use only the digits 2, 4, 6 and 8. 1
 2, 8, 22, 68, 262, 668, 6668, 66668, 666668, 6666668, 66666668, 666666668, 6666666668, 66666666668, 666666666668, 6666666666668, 66666666666668, 666666666666668, 6666666666666668, 66666666666666668, 666666666666666668, 6666666666666666668, 66666666666666666668 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Generated with DrScheme. From Bernard Schott, May 04 2022: (Start) All terms end with 2 or 8, because when k ends with 4 or 6, the tens digit of k^2 is always odd. Squares are a subsequence of A103751. This sequence is infinite because terms of the form 8, 68, 668, 6668, ..., have respectively squares equal to 64, 4624, 446224, 44462224, ... In fact, if m = (10^k+20)/15 and k >= 2, then m^2 has successively (k-2) 4's, one 6, (k-2) 2's, and one 4 in its decimal representation; hence, A073555 \ {1} is a subsequence. (End) LINKS Michael S. Branicky, Table of n, a(n) for n = 1..43 Jonathan Wellons, Tables of Shared Digits EXAMPLE 262^2 = 68644. CROSSREFS Subsequence of A045926. Cf. A073555, A103751. Sequence in context: A178159 A262720 A321573 * A089586 A339302 A045695 Adjacent sequences: A137100 A137101 A137102 * A137104 A137105 A137106 KEYWORD base,nonn AUTHOR Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008 EXTENSIONS a(19) and beyond from Michael S. Branicky, May 04 2022 STATUS approved

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Last modified June 4 20:02 EDT 2023. Contains 363128 sequences. (Running on oeis4.)