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 A218125 #9 Apr 15 2021 13:07:31
%S A218125 1,8,56,504,4032,32760,261576,2097144,16773120,134217216,1073709000,
%T A218125 8589934584,68719210560,549755813880,4398044413896,35184372055560,
%U A218125 281474959933440,2251799813685240,18014398375002624,144115188075855864,1152921503533101120
%N A218125 Number of 8-ary sequences with primitive period n.
%H A218125 Alois P. Heinz, <a href="/A218125/b218125.txt">Table of n, a(n) for n = 0..350</a>
%F A218125 a(n) = Sum_{d|n} 8^d * mu(n/d) for n>0, a(0) = 1.
%F A218125 G.f.: 1 + 8 * Sum_{k>=1} mu(k) * x^k / (1 - 8*x^k). - _Ilya Gutkovskiy_, Apr 15 2021
%p A218125 with(numtheory):
%p A218125 a:= n-> `if`(n=0, 1, add(8^d*mobius(n/d), d=divisors(n))):
%p A218125 seq(a(n), n=0..30);
%Y A218125 Column k=8 of A143324.
%K A218125 nonn
%O A218125 0,2
%A A218125 _Alois P. Heinz_, Oct 21 2012