OFFSET
1,2
COMMENTS
There are 140 such numbers between 1 and 1000.
These numbers correspond to all the prime pairs which differ by 8 except 3 and 11.
Numbers in this sequence are those which are not 6cd - c - d - 1, 6cd + c - d, 6cd - c + d or 6cd + c + d - 1, that is, they are not (6c - 1)d - c - 1, (6c - 1)d + c, (6c + 1)d - c or (6c + 1)d + c - 1.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
Sally M. Moite, “Primeless” Sieves for Primes and for Prime Pairs Which Differ by 2m, vixra:1903.0353 (2019).
EXAMPLE
a(4) = 5, so 6(5) - 1 = 29 and 6(5) + 7 = 37 are both prime.
MAPLE
select(t -> isprime(6*t-1) and isprime(6*t+7), [$1..500]); # Robert Israel, May 27 2019
PROG
(PARI) isok(n) = isprime(6*n-1) && isprime(6*n+7); \\ Michel Marcus, Apr 16 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Sally Myers Moite, Apr 14 2019
STATUS
approved