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 A308079 Pseudoprimes to base 3 that divide a Mersenne number. 0
 10974881, 193949641, 717653129, 8762386393, 19683169273, 24802217129, 78618861353, 121271968201, 146050578391, 169905267617, 188684740591, 232153956569, 290762221753, 306091598201, 336675266287, 394233108121, 592050558553 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Members of A005935 that divide a member of A001348. Odd members k of A005935 such that the multiplicative order of 2 modulo k is a prime. Odd members k of A005935 such that A002326((k-1)/2) is prime. The known entries are proper divisors of a Mersenne number. It is not known if the Mersenne number itself can belong to this sequence. Subsequence of A052155. LINKS Mersenne Forum, Composite PRP (discussion thread). EXAMPLE 10974881 is in the sequence because it divides 2^239 - 1 (and 239 is prime), it is not a prime, but 3^10974880 === 1 (mod 10974881). PROG (PARI) forstep(n=3, +oo, 2, Mod(3, n)^(n-1)==1&&!ispseudoprime(n)&&ispseudoprime(znorder(Mod(2, n)))&&print1(n, ", ")) CROSSREFS Cf. A005935, A001348, A002326, A122094, A052155. Sequence in context: A202470 A224639 A298704 * A114680 A329224 A274834 Adjacent sequences:  A308076 A308077 A308078 * A308080 A308081 A308082 KEYWORD nonn AUTHOR Jeppe Stig Nielsen, May 11 2019 STATUS approved

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Last modified May 11 21:35 EDT 2021. Contains 343808 sequences. (Running on oeis4.)