This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A376919 #14 Oct 18 2024 20:15:45
%S A376919 0,2,4,5,6,7,8,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,28,
%T A376919 29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,
%U A376919 52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70
%N A376919 The nonpowers of 3.
%C A376919 Complement of A000244. Numbers whose sum of digits in base 3 is not equal to 1.
%F A376919 For n > 0, a(n) = n + floor(log_3(n)) + 2 if n + floor(log_3(n)) + 1 >= 3^(floor(log_3(n)) + 1) and a(n) = n + floor(log_3(n)) + 1 otherwise.
%t A376919 Complement[Range[0,70],Table[3^n, {n, 0, 3}]] (* _James C. McMahon_, Oct 18 2024 *)
%o A376919 (Python)
%o A376919 from sympy import integer_log
%o A376919 def A376919(n): return n+(m:=integer_log(n,3)[0]+1)+(n+m>=3**m) if n else 0
%Y A376919 Cf. A057716, A057717, A000244.
%K A376919 nonn
%O A376919 0,2
%A A376919 _Chai Wah Wu_, Oct 10 2024