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%I #24 Jul 19 2021 19:25:53
%S 1,11,15,33,39,71,91,173,175,179,335,3337,5597,7353
%N Numbers k such that k and k^3 use only odd digits.
%C Numbers k such that k^3 uses only odd digits are in A030099.
%C No other terms below 10^16. The sequence is likely finite. - _Max Alekseyev_, Oct 17 2017
%C a(15) > 10^19, if it exists. - _Giovanni Resta_, Mar 13 2020
%e 15 is a term because both 15 and 15^3=3375 use only odd digits.
%t Select[Range[10000],And@@OddQ[Join[IntegerDigits[#],IntegerDigits[ #^3]]]&] (* _Harvey P. Dale_, May 15 2012 *)
%o (PARI) isoddd(n) = #select(x->((x%2) == 0), digits(n)) == 0;
%o isok(n) = isoddd(n) && isoddd(n^3); \\ _Michel Marcus_, Dec 03 2016
%Y Cf. A030099.
%K nonn,base,more
%O 1,2
%A _Zak Seidov_, Jul 06 2003
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