A306097 Terms of A121707 not in A267999.

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

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