A085597 Numbers k such that k and k^3 use only odd digits.

1, 11, 15, 33, 39, 71, 91, 173, 175, 179, 335, 3337, 5597, 7353

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..14.

Example

15 is a term because both 15 and 15^3=3375 use only odd digits.

Mathematica

Select[Range[10000], And@@OddQ[Join[IntegerDigits[#], IntegerDigits[ #^3]]]&] (* Harvey P. Dale, May 15 2012 *)

Prog

(PARI) isoddd(n) = #select(x->((x%2) == 0), digits(n)) == 0;
isok(n) = isoddd(n) && isoddd(n^3); \\ Michel Marcus, Dec 03 2016

Crossrefs

Cf. A030099.

Sequence in context: A009433 A275242 A030099 * A316643 A373610 A097512

Adjacent sequences: A085594 A085595 A085596 * A085598 A085599 A085600

Keyword

nonn,base,more

Author

Zak Seidov, Jul 06 2003

Status

approved