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, 14493, 14798, 16653, 17372
Offset: 1
Programs
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PARI
is(k) = ispseudoprime(lcm(primes([2, 2*k]))*2^k-1); \\ Jinyuan Wang, Mar 20 2020
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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
Extensions
a(31) from Jinyuan Wang, Mar 20 2020
a(32) from Daniel Suteu, Mar 20 2020
a(33)-a(36) from Michael S. Branicky, Jun 26 2024
Comments