A131625 Numbers k such that decimal expansion of 3^k contains no 2.

0, 1, 2, 4, 8, 9, 10, 11, 12, 15, 20, 22, 29, 34, 35, 54, 59

Offset: 1

Author

Shyam Sunder Gupta, Sep 01 2007

Keywords

• base
• fini
• nonn
• more

Comments

I conjecture that 59 is the last term.

Crossrefs

Cf. similar sequences listed in A131613.

Cf. A007377.

Programs

Magma

[n: n in [0..1000] | not 2 in Intseq(3^n)]; // Vincenzo Librandi, May 06 2015

Mathematica

Join[{0}, Select[ Range@10000, FreeQ[ IntegerDigits[3^# ], 2] &]]

PARI

isok(n) = ! vecsearch(Set(digits(3^n)), 2); \\ Michel Marcus, Feb 09 2018

Extensions

Initial 0 added and Mathematica code adapted by Vincenzo Librandi, May 06 2015