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A087967 Integers m such that gcd(-1+2^m, m^2) is not a square number. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A131766 A154575 A097926 * A070224 A083211 A156903

Adjacent sequences:  A087964 A087965 A087966 * A087968 A087969 A087970

KEYWORD

nonn

AUTHOR

Labos Elemer, Sep 22 2003

STATUS

approved

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Last modified September 19 14:36 EDT 2020. Contains 337178 sequences. (Running on oeis4.)