A131615 Numbers k such that the decimal expansion of 3^k contains no 7.

0, 1, 2, 4, 5, 8, 9, 10, 12, 13, 17, 21, 22, 24, 26, 30, 32, 33, 36, 42, 46, 66, 101

Offset: 1

Author

Shyam Sunder Gupta, Sep 01 2007

Keywords

• base
• fini
• nonn

Comments

I conjecture that 101 is the last term.

Crossrefs

Cf. similar sequences listed in A131613.

Cf. A007377.

Programs

Magma

[n: n in [0..1000] | not 7 in Intseq(3^n)]; // Vincenzo Librandi, May 06 2015

Mathematica

Select[ Range@10000, FreeQ[ IntegerDigits[3^# ],7] &]

Extensions

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