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A247205 Numbers n such that 2*n^2 - 1 divides 2^n - 1. 1
1, 18480, 8388480 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(4) > 2*10^10. - Chai Wah Wu, Dec 06 2014

LINKS

Table of n, a(n) for n=1..3.

EXAMPLE

1 is in this sequence because 2*1^2 - 1 = 1 divides 2^1 - 1 = 1.

PROG

(MAGMA) [n: n in [1..100000] | Denominator((2^n-1)/(2*n^2-1)) eq 1];

(PARI) for(n=1, 10^9, if(Mod(2, 2*n^2-1)^n==+1, print1(n, ", "))); \\ Joerg Arndt, Nov 30 2014

CROSSREFS

Cf. A247219, A247221.

Sequence in context: A209895 A190110 A157738 * A173274 A237012 A031817

Adjacent sequences:  A247202 A247203 A247204 * A247206 A247207 A247208

KEYWORD

nonn,more,bref

AUTHOR

Juri-Stepan Gerasimov, Nov 30 2014

EXTENSIONS

a(3) from Joerg Arndt, Nov 30 2014

STATUS

approved

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Last modified October 14 00:32 EDT 2019. Contains 327991 sequences. (Running on oeis4.)