OFFSET
1,1
EXAMPLE
2^135 = 435561429658801233233119497{512}66331066368.
MATHEMATICA
sub2[n_] := Block[{s = ToString[2^n], k = n - 1}, While[k >= 0 && ! StringContainsQ[s, ToString[2^k]], k--]; k]; Select[Range[574], sub2[#] == 9 &] (* Giovanni Resta, Oct 14 2019 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jun 15 1998
STATUS
approved