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A187730 Greatest common divisor of Carmichael lambda(n) and n - 1. 4
1, 1, 2, 1, 4, 1, 6, 1, 2, 1, 10, 1, 12, 1, 2, 1, 16, 1, 18, 1, 2, 1, 22, 1, 4, 1, 2, 3, 28, 1, 30, 1, 2, 1, 2, 1, 36, 1, 2, 1, 40, 1, 42, 1, 4, 1, 46, 1, 6, 1, 2, 3, 52, 1, 2, 1, 2, 1, 58, 1, 60, 1, 2, 1, 4, 5, 66, 1, 2, 3, 70, 1, 72, 1, 2, 3, 2, 1, 78, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

n is a Giuga number and A002322(n)/a(n) divides k if and only if 1^(k*(n-1)) + 2^(k*(n-1)) +...+ (n-1)^(k*(n-1)) = -1 (mod n).

LINKS

Table of n, a(n) for n=1..80.

J. M. Grau and Antonio Oller-Marcén, Generalizing Giuga's conjecture, arXiv:1103.3483 [math.NT], 2011.

MATHEMATICA

Table[GCD[CarmichaelLambda[n], n-1], {n, 100}]

PROG

(PARI) a(n) = gcd(lcm(znstar(n)[2]), n-1); \\ Michel Marcus, Mar 18 2016

CROSSREFS

Cf. A002322 (Carmichael lambda function).

Sequence in context: A258409 A060680 A057237 * A049559 A063994 A268336

Adjacent sequences:  A187727 A187728 A187729 * A187731 A187732 A187733

KEYWORD

nonn

AUTHOR

José María Grau Ribas, Mar 13 2011

STATUS

approved

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Last modified May 26 07:44 EDT 2019. Contains 323579 sequences. (Running on oeis4.)