A333390 Numbers k such that (2*k)# * 2^k - 1 is prime.

1, 2, 3, 4, 5, 12, 17, 22, 26, 28, 30, 50, 120, 186, 215, 246, 323, 1021, 1160, 1404, 1431, 1461, 1786, 2317, 2960, 4484, 4613, 5192, 5345, 6518, 6865, 9951

Offset

1,2

Comments

No more terms < 6700.

No more terms < 10^4. - Daniel Suteu, Mar 20 2020

Links

Table of n, a(n) for n=1..32.

Prog

(Python)
from sympy.ntheory.generate import primorial, isprime
A333390_list = [n for n in range(1, 100) if isprime(primorial(2*n, nth=False)*2**n-1)] # Chai Wah Wu, Mar 18 2020
(PARI) is(k) = ispseudoprime(lcm(primes([2, 2*k]))*2^k-1); \\ Jinyuan Wang, Mar 20 2020

Crossrefs

Cf. A034386 (n#), A084406.

Sequence in context: A103651 A093713 A057472 * A367408 A117577 A109849

Adjacent sequences: A333387 A333388 A333389 * A333391 A333392 A333393

Keyword

nonn,hard,more

Author

L. Joris Perrenet, Mar 18 2020

Extensions

a(31) from Jinyuan Wang, Mar 20 2020

a(32) from Daniel Suteu, Mar 20 2020

Status

approved