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A231371 Squarefree composite numbers n such that 8 is a primitive root for all prime factors of n. 2
15, 33, 55, 87, 145, 159, 165, 177, 249, 265, 295, 303, 319, 321, 393, 415, 435, 447, 505, 519, 535, 537, 583, 591, 649, 655, 681, 745, 795, 807, 865, 879, 885, 895, 913, 951, 957, 985, 1041, 1111, 1135, 1167, 1177, 1245, 1257, 1329, 1345, 1383, 1401, 1441 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If k is the smallest integer satisfying 10^k == 1 (mod p), we say that 10 has order k (mod p). If n is the product of distinct primes p(i), the period of 1/n in base a is the least common multiple of the orders of a (mod p(i)), provided a and n are relatively prime.

LINKS

Table of n, a(n) for n=1..50.

Eric Weisstein's World of Mathematics, Primitive Root

Wikipedia, Octal

CROSSREFS

Subsequence of A024556.

Cf. A019338, A231370, A231372.

Sequence in context: A071965 A242677 A020184 * A228318 A228321 A277385

Adjacent sequences:  A231368 A231369 A231370 * A231372 A231373 A231374

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Nov 08 2013

STATUS

approved

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Last modified August 7 12:19 EDT 2020. Contains 336276 sequences. (Running on oeis4.)