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

Author

Zak Seidov, Jul 06 2003

Keywords

• nonn
• base
• more

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

Examples

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

Crossrefs

Cf. A030099.

Programs

Mathematica

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

PARI

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