OFFSET
1,1
LINKS
Jinyuan Wang, Table of n, a(n) for n = 1..2000
MATHEMATICA
Select[Range[68000], And @@ PrimeQ /@ ({2, 4, 6, 8}*# + 1) &] (* Ray Chandler, Nov 20 2006 *)
PROG
(PARI) is(k) = sum(j = 1, 4, isprime(2*j*k+1)) == 4; \\ Jinyuan Wang, Aug 04 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Oct 31 2006
STATUS
approved