A316908 a(n) is the smallest k with n prime factors such that 2^(k-1) == 1 (mod k) and p-1 does not divide k-1 for every prime p dividing k.

7957, 617093, 134564501, 384266404601, 8748670222601, 6105991025919737, 901196605940857381

Offset: 2

Author

Thomas Ordowski, Jul 16 2018

Keywords

• nonn
• more

Comments

Conjecture: a(n) > A006931(n) for every n > 2.

a(6)-a(8) derived from Feitsma's tables of pseudoprimes. a(9) > 2^64. - Giovanni Resta, Jul 19 2018

From Daniel Suteu, Jun 08 2020: (Start)

a(9) <= 521957994426556057126261,

a(10) <= 1315856103949347820015303981,

a(11) <= 6357507186189933506573017225316941,

a(12) <= 77822245466150976053960303855104674781. (End)

Links

• Jan Feitsma and William Galway, Tables of pseudoprimes and related data

Crossrefs

Cf. A001567, A121707, A316907.

Extensions

More terms from Michel Marcus, Jul 16 2018

a(6)-a(8) from Giovanni Resta, Jul 19 2018