A167915 Primes which are the sums of two consecutive nonprimes (A141468).

5, 17, 19, 29, 31, 41, 43, 53, 67, 71, 79, 89, 97, 101, 103, 109, 113, 127, 131, 137, 139, 149, 151, 163, 173, 181, 191, 197, 199, 211, 223, 229, 233, 239, 241, 251, 257, 269, 271, 281, 283, 293, 307, 311, 317, 331, 337, 349, 353, 367, 373, 379, 389, 401, 409

Offset

1,1

Comments

Five together with primes that are the sum of two consecutive composite numbers.

Links

G. C. Greubel, Table of n, a(n) for n = 1..10000

Formula

a(n+1) = A060254(n) = A176902(n+1). - Juri-Stepan Gerasimov, Apr 28 2010

Example

a(1)=1+4=5, a(2)=8+9=17.

Mathematica

2*Select[Range[300], !PrimeQ[#] == !PrimeQ[#+1] && PrimeQ[2*#+1] &] + 1 (* G. C. Greubel, Jul 01 2016; Nov 10 2023 *)

Prog

(Magma) [2*n+1: n in [1..300] | (not IsPrime(n) eq not IsPrime(n+1)) and IsPrime(2*n+1)]; // G. C. Greubel, Nov 10 2023
(SageMath) [2*n+1 for n in (1..300) if  (not is_prime(n)) - (not is_prime(n+1)) == 0 and is_prime(2*n+1)] # G. C. Greubel, Nov 10 2023

Crossrefs

Cf. A000040, A060254, A141468, A176902.

Sequence in context: A117382 A191076 A166685 * A019373 A140568 A019349

Adjacent sequences: A167912 A167913 A167914 * A167916 A167917 A167918

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 15 2009

Extensions

Typo corrected and terms checked by D. S. McNeil, Nov 17 2010

Status

approved