A070191 - OEIS

A070191

Numbers k such that gcd(3*k, 8^k+1) = 3.

1, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47, 49, 53, 59, 61, 65, 67, 71, 73, 77, 79, 83, 85, 89, 91, 95, 97, 101, 103, 107, 109, 113, 115, 119, 121, 125, 127, 131, 133, 137, 139, 143, 145, 149, 151, 155, 157, 161, 163, 167, 169, 173, 175, 179, 181

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OFFSET

1,2

COMMENTS

The listed terms are the same as those in A069040, but the sequences are not identical. (The similarity is mostly explained by the absence of multiples of 2, 3 and 55 from both sequences.) See A070192 and A070193 for the differences.

The number of terms not exceeding 10^m, for m = 1, 2, ..., are 3, 32, 325, 3244, 32468, 324667, 3246642, 32466291, 324662816, 3246627133, ... . Apparently, the asymptotic density of this sequence exists and equals 0.32466... . - Amiram Eldar, Jun 14 2022

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

MATHEMATICA

test8[n_] := GCD[3n, PowerMod[8, n, 3n]+1]==3; Select[Range[200], test8]

CROSSREFS

Cf. A069254.

Cf. A069040, A070192, A070193.

Sequence in context: A339911 A007310 A069040 * A367734 A231810 A314294

Adjacent sequences: A070188 A070189 A070190 * A070192 A070193 A070194

KEYWORD

nonn

AUTHOR

Benoit Cloitre and Dean Hickerson, Apr 26 2002

STATUS

approved