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A085597
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Numbers k such that k and k^3 use only odd digits.
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2
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1, 11, 15, 33, 39, 71, 91, 173, 175, 179, 335, 3337, 5597, 7353
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OFFSET
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1,2
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COMMENTS
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Numbers k such that k^3 uses only odd digits are in A030099.
No other terms below 10^16. The sequence is likely finite. - Max Alekseyev, Oct 17 2017
a(15) > 10^19, if it exists. - Giovanni Resta, Mar 13 2020
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LINKS
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Table of n, a(n) for n=1..14.
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EXAMPLE
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15 is a term because both 15 and 15^3=3375 use only odd digits.
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MATHEMATICA
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Select[Range[10000], And@@OddQ[Join[IntegerDigits[#], IntegerDigits[ #^3]]]&] (* Harvey P. Dale, May 15 2012 *)
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PROG
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(PARI) isoddd(n) = #select(x->((x%2) == 0), digits(n)) == 0;
isok(n) = isoddd(n) && isoddd(n^3); \\ Michel Marcus, Dec 03 2016
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CROSSREFS
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Cf. A030099.
Sequence in context: A009433 A275242 A030099 * A316643 A097512 A032490
Adjacent sequences: A085594 A085595 A085596 * A085598 A085599 A085600
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KEYWORD
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nonn,base,more
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AUTHOR
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Zak Seidov, Jul 06 2003
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STATUS
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approved
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