Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #20 Dec 11 2020 19:23:31
%S 1,18,20,22,41,43,62,64,66,83,85,87,106,108,110,127,129,131,150,152,
%T 171,173,175,194,196,215,217,219,236,238,240,259,261,263,280,282,284,
%U 303,305,324,326,328,347,349,368,370,372,389,391,393,412,414,416,433
%N Numbers n such that 3 is the first digit of 3^n.
%H Vincenzo Librandi, <a href="/A054565/b054565.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[500],First[IntegerDigits[3^#]]==3&] (* _Harvey P. Dale_, Dec 23 2012 *)
%o (PARI) for(n=1,100, if(floor(3^n/10^(floor(n*log(3)/log(10))))==3,print1(n,",")))
%Y Cf. A067481.
%K nonn,base
%O 1,2
%A _Benoit Cloitre_, Feb 22 2002
%E Corrected by _T. D. Noe_, Nov 01 2006
%E Corrected by _Harvey P. Dale_, Dec 23 2012