A170820 - OEIS

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A170820

Let p = n-th prime; a(n) = (p-1)/(order of (p+3)/2 mod p).

2, 1, 1, 3, 1, 6, 2, 4, 1, 1, 1, 2, 2, 4, 1, 5, 2, 10, 2, 3, 1, 1, 12, 4, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 5, 2, 2, 4, 3, 42, 1, 1, 1, 1, 2, 8, 1, 1, 2, 4, 1, 1, 7, 2, 4, 6, 2, 2, 4, 30, 2, 1, 1, 1, 2, 1, 3, 2, 2, 2, 1, 25, 4, 11, 1, 10, 2, 3, 1, 1, 8, 10, 33, 1, 2, 3, 1, 6, 2, 4, 1, 2, 1, 2, 2, 1

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OFFSET

3,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 3..65536

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.

MAPLE

with(numtheory); [seq((ithprime(n)-1)/order((ithprime(n)+3)/2, ithprime(n)), n=3..130)];

MATHEMATICA

a[n_] := Module[{p=Prime[n]}, (p-1)/MultiplicativeOrder[(p+3)/2, p]]; Array[a, 100, 3] (* Amiram Eldar, Dec 03 2018 *)

PROG

(PARI) a(n) = my(p=prime(n)); (p-1)/znorder(Mod((p+3)/2, p)); \\ Michel Marcus, Dec 03 2018

CROSSREFS

Cf. A014664, A001917, A170821, A170822.

Sequence in context: A348447 A277606 A228267 * A339615 A003687 A104575

Adjacent sequences: A170817 A170818 A170819 * A170821 A170822 A170823

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 24 2009

STATUS

approved