A131617 Numbers k such that the decimal expansion of 3^k contains no 5.

0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 14, 15, 16, 17, 18, 19, 20, 23, 25, 29, 31, 41, 44, 52, 58, 81, 91

Offset: 1

Author

Shyam Sunder Gupta, Sep 01 2007

Keywords

• base
• fini
• nonn

Comments

I conjecture that 91 is the last term.

Crossrefs

Cf. similar sequences listed in A131613.

Cf. A007377.

Programs

Magma

[n: n in [0..1000] | not 5 in Intseq(3^n) ]; // Vincenzo Librandi, May 06 2015

Mathematica

Join[{0}, Select[ Range@10000, FreeQ[ IntegerDigits[3^# ], 5] &]]

Extensions

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