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A130693
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Powers of 2 whose digits are powers of 2.
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1
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OFFSET
| 1,2
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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 (deutsch(AT)duke.poly.edu), 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 (noe(AT)sspectra.com), Apr 05 2008
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REFERENCES
| David Wells, "The Penguin Dictionary of Curious and Interesting Numbers" (1997), p. 123.
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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 (deutsch(AT)duke.poly.edu), Jul 15 2007
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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 (noe(AT)sspectra.com), Apr 05 2008
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CROSSREFS
| Sequence in context: A018713 A007633 A018777 * A060815 A200758 A110746
Adjacent sequences: A130690 A130691 A130692 * A130694 A130695 A130696
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KEYWORD
| nonn,base
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AUTHOR
| Gregory P. Dresden (dresdeng(AT)wlu.edu), Jul 09 2007
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