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Numbers k such that k is a substring of 8^k.
3

%I #23 Feb 19 2024 01:56:20

%S 4,6,7,10,13,17,18,28,31,33,36,38,42,44,47,48,49,52,54,56,58,60,63,64,

%T 67,68,69,76,77,79,81,82,83,85,86,89,90,91,94,97,112,115,124,130,135,

%U 165,173,176,178,189,193,195,206,208,215,221,225,249,251,252,253,256

%N Numbers k such that k is a substring of 8^k.

%H David A. Corneth, <a href="/A049306/b049306.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[300],SequenceCount[IntegerDigits[8^#],IntegerDigits[#]]>0&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 16 2018 *)

%o (Python)

%o def ok(n): return str(n) in str(8**n)

%o print(list(filter(ok, range(257)))) # _Michael S. Branicky_, Aug 13 2021

%Y Cf. A001018, A032740, A049301-A049307.

%K nonn,base,easy

%O 1,1

%A _David W. Wilson_