A087967 Integers m such that gcd(-1+2^m, m^2) is not a square number.

18, 36, 72, 90, 100, 126, 144, 147, 162, 180, 198, 200, 234, 252, 288, 294, 300, 306, 324, 342, 360, 396, 400, 414, 441, 450, 468, 504, 522, 558, 576, 588, 600, 612, 630, 648, 666, 684, 700, 720, 735, 738, 774, 792, 800, 810, 828, 846, 882, 900, 936, 954

Offset

1,1

Links

Table of n, a(n) for n=1..52.

Formula

Solutions x to Integer[Sqrt[GCD[ -1+2^x, x^2]]]=False.

Example

m=18: gcd(262143,324) = 27 is not a square number, so 18 is a term.

Prog

(PARI) isok(m) = !issquare(gcd(2^m-1, m^2)); \\ Michel Marcus, Aug 27 2019

Crossrefs

Cf. A087966, A087969.

Sequence in context: A154575 A344199 A097926 * A070224 A083211 A156903

Adjacent sequences: A087964 A087965 A087966 * A087968 A087969 A087970

Keyword

nonn

Author

Labos Elemer, Sep 22 2003

Status

approved