A357125 Positive integers n such that 2^(n-3) == -1 (mod n).

1, 5, 4553, 46777, 82505, 4290773, 4492205, 4976429, 21537833, 21549349, 51127261, 56786089, 60296573, 80837773, 87761789, 94424465, 138644873, 168865001, 221395541, 255881453, 297460453, 305198249, 360306365, 562654205, 635374253, 673867253, 808333573, 1164757553, 1210317349

Offset: 1

Author

Max Alekseyev, Sep 13 2022

Keywords

• nonn

Comments

Also, odd integers n dividing 2^n + 8.

Some large terms: 5603900696716667005, 446661376165868432471569407934747098747181600670953926245, 1533278864164902082788937853692280620552397221686019535813.

Links

• Max Alekseyev, Table of n, a(n) for n = 1..781 (all terms below 10^15)

Crossrefs

The odd terms of A245319.

Cf. A006521, A115976, A276967, A251603.

Programs

Mathematica

Select[Range[2155*10^4],PowerMod[2,#-3,#]==#-1&]//Quiet (* The program generates the first 10 terms of the sequence. *) (* Harvey P. Dale, Feb 08 2025 *)