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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 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.)