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A157200
Numbers k such that k*(2k)^k - 1 is a prime.
0
2, 3, 6, 7, 12, 21, 113, 404, 735, 1944, 4973, 17459
OFFSET
1,1
COMMENTS
Conjecture: there are infinitely many such primes.
a(12) > 10000. - Donovan Johnson, Aug 31 2010
EXAMPLE
2*(2*2)^2 - 1 = 31 is prime, so 2 is a term;
3^(2*3)^2 - 1 = 107 is prime, so 3 is a term.
MATHEMATICA
Do[cp=n*(2*n)^n-1; If[PrimeQ[cp], Print[n]], {n, 1, 2000}] (* generates the first 10 terms *)
PROG
(PARI) is(n)=ispseudoprime(n*(2*n)^n-1) \\ Charles R Greathouse IV, Jun 17 2013
CROSSREFS
Sequence in context: A144120 A375401 A073712 * A255940 A167415 A354361
KEYWORD
hard,nice,nonn,more
AUTHOR
Lei Zhou, Feb 25 2009
EXTENSIONS
a(11) from Donovan Johnson, Aug 31 2010
a(12) from Michael S. Branicky, Aug 31 2024
STATUS
approved