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A365063
Least k such that k*A000668(n)*A000668(n+2) + 1 is prime, where A000668(n) is the n-th Mersenne prime.
2
4, 4, 6, 34, 4, 18, 4, 10, 34, 60, 208, 442, 976, 1548, 1918, 1726, 3828, 210, 17940, 34254, 1852, 19986, 7728, 22186, 9966
OFFSET
1,1
COMMENTS
If they exist, a(26) > 31373, a(27) > 419, a(28) > 87.
MATHEMATICA
Table[k=1; Monitor[Parallelize[While[True, If[PrimeQ[k*(2^MersennePrimeExponent[n]-1)*(2^(MersennePrimeExponent[n+2])-1)+1], Break[]]; k++]; k], k], {n, 1, 25}]
CROSSREFS
Cf. A000668 (Mersenne primes), A098917, A365064, A365065.
Sequence in context: A264578 A261146 A368304 * A090531 A350581 A356686
KEYWORD
nonn,more
AUTHOR
STATUS
approved