A365064 Least k such that k*A000668(n)*A000668(n+3) + 1 is prime, where A000668(n) is the n-th Mersenne prime.

6, 10, 22, 30, 16, 12, 6, 238, 28, 58, 178, 324, 346, 214, 2664, 4744, 24298, 5236, 2526, 3756, 6792, 2778, 1872, 59128

Offset

1,1

Comments

a(25) > 53268 from Robert P. P. McKone, Aug 20 2023.

If they exist, a(26) > 275, a(27) > 119.

Links

Table of n, a(n) for n=1..24.

Mathematica

Table[k=1; Monitor[Parallelize[While[True, If[PrimeQ[k*(2^MersennePrimeExponent[n]-1)*(2^(MersennePrimeExponent[n+3])-1)+1], Break[]]; k++]; k], k], {n, 1, 20}]

Crossrefs

Cf. A000668 (Mersenne primes), A098917, A365063, A365065.

Sequence in context: A082419 A102783 A369656 * A157037 A189992 A255746

Adjacent sequences: A365061 A365062 A365063 * A365065 A365066 A365067

Keyword

nonn,more

Author

J.W.L. (Jan) Eerland, Aug 19 2023

Extensions

a(24) from Robert P. P. McKone, Aug 20 2023

Status

approved