OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(3) = 71 is a term because with k = (71^2-1)/6 = 840, 71, 71+840 = 911 and 71^2+840 = 5881 are all primes.
MAPLE
select(p -> isprime(p) and isprime((7*p^2-1)/6) and isprime((p^2+6*p-1)/6), [seq(seq(6*i+j, j=[1, 5]), i=0..10000)]);
PROG
(PARI) isok(p) = isprime(p) && iferr(isprime(p+(p^2-1)/6) && isprime(p^2+(p^2-1)/6), E, 0); \\ Michel Marcus, Dec 23 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 22 2020
STATUS
approved