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 A216322 #11 Sep 23 2012 21:20:46 %S A216322 1,1,1,1,1,2,2,2,2,4,0,2,2,2,4,4,2,6,0,2,4,10,0,4,4,6,0,6,0,8,8,4,8,4, %T A216322 0,6,6,4,0,8,0,12,8,4,10,22,8,12,8,8,8,12,6,8,8,6,12,28,8,8,8,6,16,8, %U A216322 8,20,16,10,8,24,8,12,12,8,12,8,8,24,16,18,16,40,8,16,12 %N A216322 Number of primitive roots Modd n (see A216321). %C A216322 This sequence coincides with A216321 for all n values from A206551 (cyclic multiplicative Modd n group) and the entry is 0 otherwise (if no primitive root exists, that is, n is from the complementary sequence A206552). %F A216322 a(n) = A216321(n) if n belongs to the sequence A206551 and a(n)=0 if n belongs to A206552. %e A216322 a(8) = phi(phi(2*8)/2) = 2 , with phi = A000010, because 8 = A206551(8). %e A216322 a(12) = 0 because 12 = A206552(1). %Y A216322 Cf. A216321, A046144 (modulo n analog). %K A216322 nonn %O A216322 1,6 %A A216322 _Wolfdieter Lang_, Sep 21 2012