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 A366664 #13 Jul 04 2024 15:01:45 %S A366664 1,2,2,3,3,3,3,4,2,4,3,4,6,4,4,5,2,4,4,4,5,7,5,4,4,6,4,5,6,4,7,5,2,6, %T A366664 5,8,8,5,6,7,5,5,10,7,6,8,4,4,6,9,6,8,7,6,9,7,9,9,5,3,11,6,4,11,6,7,9, %U A366664 9,7,6,9,5,6,6,6,11,4,8,7,5,4,7,5,5,11 %N A366664 Number of distinct prime divisors of 9^n + 1. %H A366664 Max Alekseyev, <a href="/A366664/b366664.txt">Table of n, a(n) for n = 0..345</a> %F A366664 a(n) = omega(9^n+1) = A001221(A062396(n)). %F A366664 a(n) = A366580(2*n). - _Max Alekseyev_, Jan 08 2024 %t A366664 PrimeNu[9^Range[0,90]+1] (* _Harvey P. Dale_, Jul 04 2024 *) %o A366664 (PARI) for(n = 0, 100, print1(omega(9^n + 1), ", ")) %Y A366664 Cf. A062396, A001221, A057935, A366660, A366665, A366666, A366667. %Y A366664 Cf. A046799, A366580, A366605, A366615, A366627, A366636, A366655, A119704, A366686, A366712. %K A366664 nonn %O A366664 0,2 %A A366664 _Sean A. Irvine_, Oct 15 2023