OFFSET
1,1
COMMENTS
Primes = 1 or 23 mod 24. Hence, together with 2, primes such that (2/p) = 1 = (3/p) where (k/p) is the Legendre symbol. - Charles R Greathouse IV, Apr 06 2012
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[ Range[2000], PrimeQ[ # ]&&Mod[ PowerMod[3, (#+1)/2, # ] - PowerMod[2, (#+1)/2, # ] - 1, # ]==0&]
Select[Prime[Range[250]], Divisible[3^((#+1)/2)-2^((#+1)/2)-1, #]&] (* Harvey P. Dale, Mar 21 2021 *)
PROG
(PARI) is(n)=(n+1)%24<3 && isprime(n) \\ Charles R Greathouse IV, Apr 06 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alexander Adamchuk, May 05 2007
STATUS
approved