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 A113913 #8 Jan 21 2019 19:01:55
%S A113913 1,2,4,6,11,20,27
%N A113913 Number of distinct prime factors of 3^(3^n)+1.
%C A113913 The term omega(3^(3^6)+1) was obtained with ECM factoring.
%F A113913 a(n) = A001221(A129290(n)).
%t A113913 Table[PrimeNu[3^(3^n) + 1], {n,1,10}] (* _G. C. Greubel_, May 16 2017 *)
%o A113913 (PARI) for(x=1,6,print1( omega(3^(3^x)+1),","))
%K A113913 hard,more,nonn
%O A113913 0,2
%A A113913 _Jorge Coveiro_, Jan 29 2006