OFFSET
3,2
LINKS
I. Anderson and D. A. Preece, Combinatorially fruitful properties of 3*2^(-1) and 3*2^(-2) modulo p, Discr. Math., 310 (2010), 312-324.
EXAMPLE
n=3: p=5, A170821(n)=2, order of 2 mod 5 = 4, (5-1)/4 = 1 = a(3).
PROG
(PARI) f(n) = my(p=prime(n), k=0); while(Mod(4*k, p) != 3, k++); k; \\ A170821
a(n) = my(p=prime(n)); (p-1)/znorder(Mod(f(n), p)); \\ Michel Marcus, Dec 04 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 24 2009
STATUS
approved