A131617 - OEIS

%I #10 Sep 08 2022 08:45:31

%S 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,

%T 91

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

%C I conjecture that 91 is the last term.

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

%o (Magma) [n: n in [0..1000] | not 5 in Intseq(3^n) ]; // _Vincenzo Librandi_, May 06 2015

%Y Cf. similar sequences listed in A131613.

%Y Cf. A007377.

%K base,fini,nonn

%O 1,3

%A _Shyam Sunder Gupta_, Sep 01 2007

%E Initial 0 added and Mathematica code adapted by _Vincenzo Librandi_, May 06 2015