%I
%S 1,2,4,8,128
%N Powers of 2 whose digits are powers of 2.
%C It is unknown if there are any other powers of 2 with this property (that is, the digits are composed only of the numbers 1,2,4,8).
%C No more powers of 2 with this property up to 2^(70000) (Saunders, J. of Recreational Mathematics, v. 26, p. 151).  _Emeric Deutsch_, Jul 15 2007
%C By looking at just the lowest 20 digits of the powers of 2, the Mathematica program shows that there are no other terms less than 2^10000000.  _T. D. Noe_, Apr 05 2008
%D David Wells, "The Penguin Dictionary of Curious and Interesting Numbers" (1997), p. 123.
%p a := proc (n) if `subset`(convert(convert(2^n, base, 10), set), {1, 2, 4, 8}) then 2^n else end if end proc: seq(a(n), n = 0 .. 300); # _Emeric Deutsch_, Jul 15 2007
%t pwr=1; Do[pwr=Mod[2*pwr,10^20]; d=Union[IntegerDigits[pwr]]; If[Intersection[d,{3,5,6,7,9,0}]=={}, Print[n]], {n,10000000}] (* _T. D. Noe_, Apr 05 2008 *)
%K nonn,base
%O 1,2
%A _Greg Dresden_, Jul 09 2007
