OFFSET
1,1
COMMENTS
This sequence includes the known solutions of Brocard's problem as of 2016 (see A146968).
EXAMPLE
3 is in the sequence because 3! = 6, sqrt(6) = 2.449489742783178..., the ceiling of which is 3, which is prime.
4 is in the sequence because 4! = 24, sqrt(24) = 4.898979485566356..., the ceiling of which is 5, which is prime.
MATHEMATICA
Select[Range[3200]], PrimeQ[Ceiling[Sqrt[#!]]] &]
PROG
(Python)
from math import isqrt, factorial
from itertools import count, islice
from sympy import isprime
def A273932_gen(): # generator of terms
return filter(lambda n:isprime(1+isqrt(factorial(n)-1)), count(1))
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Salvador Cerdá, Jun 04 2016
EXTENSIONS
a(9) from Giovanni Resta, Jun 20 2016
STATUS
approved