A279027 a(n) = number of primes of the form 4k + 3 such that 2n - 4k - 3 is prime.

0, 0, 1, 1, 2, 1, 3, 2, 2, 2, 3, 3, 4, 2, 4, 2, 4, 4, 3, 3, 4, 3, 3, 5, 6, 3, 6, 3, 2, 6, 5, 5, 6, 2, 6, 6, 6, 5, 8, 4, 6, 8, 7, 4, 12, 4, 5, 7, 4, 6, 8, 5, 6, 8, 8, 7, 10, 6, 5, 12, 4, 5, 10, 3, 8, 9, 7, 5, 10, 7, 7, 11, 8, 5, 14, 4, 8, 11, 7, 8, 10, 5, 5, 13, 12, 6, 14, 7, 6, 14, 10, 8, 14

Offset

1,5

Comments

Conjecture: a(n) > 0 for n >= 3.

Links

Table of n, a(n) for n=1..93.

Example

a(5) = 2 because 2*5 - 4*0 - 3 = 7 is prime where 4*0 + 3 = 3 is prime of the form 4k+3 and 2*5 - 4*1 - 3 = 3 is prime where 4*1 + 3 = 7 is prime of the form 4k+3.

Crossrefs

Cf. A002145, A280134.

Sequence in context: A273568 A140720 A033559 * A103151 A035221 A035191

Adjacent sequences: A279024 A279025 A279026 * A279028 A279029 A279030

Keyword

nonn

Author

Juri-Stepan Gerasimov, Dec 31 2016

Status

approved