OFFSET

1,3

COMMENTS

Or, numbers k such that there is no prime p < 2k with 2k - p and 2k + p both prime.

The two initial terms vacuously satisfy the definition, but all even numbers >= 4 are the sum of two primes, according to the Goldbach conjecture.

See also A284919, twice this sequence, which lists the values of 2k.

LINKS

Claudio Meller and others, New sequence, SeqFan list, April 5, 2017. (Click "next" for subsequent contributions.)

PROG

(PARI) is_A284928(n)=!forprime(p=2, n, isprime(2*n-p) && (isprime(2*n+p) || isprime(4*n-p)) && return) \\ M. F. Hasler, Apr 06 2017

CROSSREFS

KEYWORD

nonn

AUTHOR

M. F. Hasler, Apr 06 2017

STATUS

approved