%I #18 Oct 14 2019 04:26:47

%S 26,31,46,59,66,67,72,77,83,86,89,92,96,101,106,111,116,119,123,124,

%T 125,126,129,131,136,138,141,142,144,148,152,153,155,157,163,165,166,

%U 171,176,177,178,181,182,183,186,193,194,197,198,199,202,204,205,206

%N Numbers k such that 2^k contains 2^6=64 as its largest proper substring of the form 2^m.

%C If there is a term beyond a(747) = 7954, it is larger than 250000. - _Giovanni Resta_, Oct 14 2019

%H Giovanni Resta, <a href="/A046292/b046292.txt">Table of n, a(n) for n = 1..747</a>

%e 2^26 = 671088{64};

%e 2^31 = 2147483{64}8;

%e 2^46 = 703687441776{64}.

%t sub2[n_] := Block[{s = ToString[2^n], k = n - 1}, While[k >= 0 && ! StringContainsQ[s, ToString[2^k]], k--]; k]; Select[Range[300], sub2[#] == 6 &] (* _Giovanni Resta_, Oct 14 2019 *)

%Y Cf. A033921.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jun 15 1998