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A306097 Terms of A121707 not in A267999. 5
697, 1241, 1247, 1271, 1513, 2057, 2201, 2329, 2501, 2873, 3053, 3131, 3683, 3689, 3961, 4015, 4061, 4141, 4777, 4859, 4991, 5321, 5921, 5963, 6137, 6851, 6953, 7421, 7769, 7781, 7957, 8471, 8711, 8857, 9017, 9211, 9271, 9401, 9641, 9673, 10217, 10277, 10489, 10795, 11033, 11501 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that gcd(n, 2^n-2) > 1 and gcd(n, b^n-b) = 1 for some b > 2, b < n.

Or: Numbers n such that gcd(n, 2^n-2) > 1 and for every prime factor p of n, p-1 does not divide n-1.

2057 is the first term not in A008367, nor in A287391. - M. F. Hasler, Oct 04 2018

LINKS

M. F. Hasler, Table of n, a(n) for n = 1..10000

FORMULA

A121707 \ A267999.

EXAMPLE

The smallest element of this sequence is a(1) = 697 = 17*41.

PROG

(PARI) is(n, p)={for(i=1, #p=factor(n)[, 1], (n-1)%(p[i]-1)||return); gcd(n, lift(Mod(2, n)^n-2))>1}

CROSSREFS

Cf. A121707, A267999.

Sequence in context: A160206 A111105 A137559 * A185377 A118059 A028500

Adjacent sequences:  A306094 A306095 A306096 * A306098 A306099 A306100

KEYWORD

nonn

AUTHOR

M. F. Hasler, following remarks from Tomasz Ordowski, Oct 03 2018

STATUS

approved

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Last modified April 6 21:24 EDT 2020. Contains 333286 sequences. (Running on oeis4.)