OFFSET
1,1
COMMENTS
a(6) > 219976.
LINKS
Steven Harvey, Generalized Cullen Search
G. Loeh, Generalized Cullen primes
Wikipedia, Cullen number
MATHEMATICA
Select[Range[1, 10000], PrimeQ[n*20^n+1] &]
PROG
(PARI) for(n=1, 10000, if(isprime(n*20^n+1), print1(n, ", ")))
(Magma) [n: n in [1..10000] |IsPrime(n*20^n+1)]
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Tim Johannes Ohrtmann, Oct 25 2020
STATUS
approved