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A066507 Numbers n such that there is a solution to x^2 = 2^n mod(n). 1
1, 2, 4, 6, 7, 8, 10, 12, 14, 16, 17, 18, 20, 22, 23, 24, 26, 28, 30, 31, 32, 34, 36, 38, 40, 41, 42, 44, 46, 47, 48, 49, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 71, 72, 73, 74, 76, 78, 79, 80, 82, 84, 86, 88, 89, 90, 92, 94, 96, 97, 98, 100, 102, 103, 104, 106, 108, 110 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

All even numbers are in this sequence.

Odd terms in the sequence are numbers whose prime factors are +-1 mod 8 (A058529), i.e. odd n such that x^2 = 2 (mod n) has a solution. - Jason Earls, Jan 22 2002

LINKS

Table of n, a(n) for n=1..69.

PROG

(PARI) isok(n) = {for (x=0, n-1, if (Mod(x, n)^2 == Mod(2, n)^n, return (1)); ); return (0); } \\ Michel Marcus, Nov 20 2013

CROSSREFS

Cf. A058529, A001132, A057126.

Sequence in context: A153282 A014661 A047511 * A285140 A015932 A030493

Adjacent sequences:  A066504 A066505 A066506 * A066508 A066509 A066510

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 04 2002

EXTENSIONS

Corrected by Vladeta Jovovic, Jan 22 2002

More terms from Jason Earls, Jan 22 2002

STATUS

approved

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Last modified January 26 11:13 EST 2020. Contains 331279 sequences. (Running on oeis4.)