The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A130693 Powers of 2 whose digits are powers of 2. 2
 1, 2, 4, 8, 128 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 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). 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 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 REFERENCES David Wells, "The Penguin Dictionary of Curious and Interesting Numbers" (1997), p. 123. LINKS MAPLE 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 MATHEMATICA 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 *) CROSSREFS Sequence in context: A018713 A007633 A018777 * A286523 A060815 A200758 Adjacent sequences: A130690 A130691 A130692 * A130694 A130695 A130696 KEYWORD nonn,base AUTHOR Greg Dresden, Jul 09 2007 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 5 03:44 EST 2023. Contains 360082 sequences. (Running on oeis4.)