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A087967 GCD[ -1+2^n, n^2] is not a square number. 1
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

n=18: GCD[262143,324]=27=a(18) is not a square number.

CROSSREFS

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 May 26 19:25 EDT 2019. Contains 323597 sequences. (Running on oeis4.)