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A291961 Numbers n > 1 such that 2^lambda(n) == 1 (mod n^2), where lambda(n) is the Carmichael lambda function (A002322). 0
1093, 3279, 3511, 7651, 10533, 14209, 17555, 22953, 31599, 42627, 45643, 52665, 99463, 136929, 157995, 228215, 298389, 410787, 684645, 2053935, 3837523, 11512569, 19187615, 26862661, 34537707, 49887799, 57562845, 80587983, 134313305, 149663397, 172688535, 241763949, 249438995, 349214593, 402939915, 448990191, 748316985, 1047643779, 1208819745, 1746072965, 2244950955, 3142931337, 5238218895 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

An alternative generalization of Wieferich primes (A001220).

A subsequence of A077816, since the A002322(n)|A000010(n). The first 12 terms are common.

15714656685 (see A265630) is also a term. - Michel Marcus, Sep 14 2017

LINKS

Table of n, a(n) for n=1..43.

MATHEMATICA

Select[Range[2, 100000], Divisible[2^CarmichaelLambda[#] - 1, #^2] &]

PROG

(PARI) isok(n) = Mod(2, n^2)^lcm(znstar(n)[2]) == 1; \\ Michel Marcus, Sep 11 2017

CROSSREFS

Cf. A265630, A001220, A002322, A077816, A182297, A246503.

Sequence in context: A038469 A246503 A077816 * A001220 A265630 A291194

Adjacent sequences:  A291958 A291959 A291960 * A291962 A291963 A291964

KEYWORD

nonn

AUTHOR

Amiram Eldar, Sep 06 2017

EXTENSIONS

a(32)-a(36) from Michel Marcus, Sep 11 2017

a(37)-a(41) from Michel Marcus, Sep 12 2017

a(42)-a(43) from Michel Marcus, Sep 14 2017

STATUS

approved

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Last modified October 22 05:36 EDT 2021. Contains 348160 sequences. (Running on oeis4.)