cp's OEIS Frontend

A170822 Let p = n-th prime; a(n) = (p-1)/(order of A170821(n) mod p).

%I A170822 #10 Dec 04 2018 04:07:57
%S A170822 1,3,2,2,1,1,2,1,1,12,1,1,2,1,2,4,1,14,2,1,2,1,2,1,1,2,2,1,1,10,1,3,1,
%T A170822 1,4,9,2,1,2,18,2,16,1,1,1,1,2,2,1,2,6,2,1,2,1,1,2,1,1,1,3,10,12,1,1,
%U A170822 42,2,12,1,2,1,4,27,2,1,4,1,6,2,6,10,4,3,2,1,2,1,1,2,2,1,2,3,2,1,5
%N A170822 Let p = n-th prime; a(n) = (p-1)/(order of A170821(n) mod p).
%H A170822 I. Anderson and D. A. Preece, <a href="http://dx.doi.org/10.1016/j.disc.2008.09.046">Combinatorially fruitful properties of 3*2^(-1) and 3*2^(-2) modulo p</a>, Discr. Math., 310 (2010), 312-324.
%e A170822 n=3: p=5, A170821(n)=2, order of 2 mod 5 = 4, (5-1)/4 = 1 = a(3).
%o A170822 (PARI) f(n) = my(p=prime(n), k=0); while(Mod(4*k, p) != 3, k++); k; \\ A170821
%o A170822 a(n) = my(p=prime(n)); (p-1)/znorder(Mod(f(n), p)); \\ _Michel Marcus_, Dec 04 2018
%Y A170822 Cf. A001917, A170820, A170821.
%K A170822 nonn
%O A170822 3,2
%A A170822 _N. J. A. Sloane_, Dec 24 2009