A227031 Odd primes such that the previous prime is not the larger part of a twin prime pair.

3, 5, 13, 19, 29, 31, 41, 43, 53, 59, 61, 71, 73, 83, 89, 97, 101, 103, 109, 127, 131, 137, 139, 151, 163, 167, 173, 179, 181, 193, 199, 223, 227, 229, 239, 241, 257, 263, 269, 271, 281, 283, 307, 311, 313, 331, 337, 347, 349, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421

Offset: 1

Author

Irina Gerasimova, Jun 28 2013

Keywords

• nonn

Comments

This is the complement of A088176 in the set of odd primes. - R. J. Mathar, Jul 04 2013

Examples

			a(1) = 3 because 3 is prime and prevprime(3) - 2 = 2 - 2 = 0 is not prime,
a(2) = 5 because 5 is prime and prevprime(5) - 2 = 3 - 2 = 1 is not prime,
a(3) = 13 because 13 is prime and prevprime(13) - 2 = 11 - 2 = 9 is composite.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A088175, A088176.

Programs

Mathematica

Select[Prime[Range[2, 100]], Not[PrimeQ[NextPrime[#, -1] - 2]] &] (* Alonso del Arte, Jul 04 2013 *)

PARI

is(n)=n>2 && !isprime(precprime(n-2)-2) && isprime(n) \\ Charles R Greathouse IV, Mar 18 2014

Formula

a(n) ~ prime(n) ~ n log n. - Charles R Greathouse IV, Jun 28 2013