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 A157200 Numbers n such that n*(2n)^n-1 is a prime. 0
 2, 3, 6, 7, 12, 21, 113, 404, 735, 1944, 4973 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Conjecture: there are infinite numbers of such kind of primes. a(12) > 10000. [From Donovan Johnson, Aug 31 2010] LINKS EXAMPLE n=2, 2*(2*2)^2-1 = 31 is a prime number; n=3, 3^(2*3)^2-1 = 107 is a prime number; and so on MATHEMATICA Do[cp=n*(2*n)^n-1; If[PrimeQ[cp], Print[n]], {n, 1, 2000}] This generates the listed first 10 elements. PROG (PARI) is(n)=ispseudoprime(n*(2*n)^n-1) \\ Charles R Greathouse IV, Jun 17 2013 CROSSREFS Sequence in context: A238590 A144120 A073712 * A255940 A167415 A018511 Adjacent sequences:  A157197 A157198 A157199 * A157201 A157202 A157203 KEYWORD hard,nice,nonn AUTHOR Lei Zhou, Feb 25 2009 EXTENSIONS a(11) from Donovan Johnson, Aug 31 2010 STATUS approved

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Last modified December 16 03:14 EST 2019. Contains 330013 sequences. (Running on oeis4.)