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%I #6 Dec 01 2018 16:31:41
%S 0,1,2,357,358,359,449,450,2417,2450,4901,5146,34056,34301,36752,
%T 39202,39207,151326,153777,154022,156473,156506,156751,6005594,
%U 6605901,12476003,12490737,12492410,12505208,12506909,12622759,13213405
%N Base 10 integers n such that n base 7 is a substring of n base 3.
%H Zak Seidov, <a href="/A164700/b164700.txt">Table of n, a(n) for n = 1..99</a>
%e a(8)=2417 because 2417 base 10 = 10022 base 7 = 10022112 base 3, and the string 10022 appears in 10022112.
%t Select[Range[0,133*10^5],SequenceCount[IntegerDigits[#,3], IntegerDigits[ #,7]]>0&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 01 2018 *)
%K base,easy,nonn
%O 1,3
%A _Gil Broussard_, Aug 22 2009
%E More terms from _Zak Seidov_, Aug 23 2009