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A227031
Odd primes such that the previous prime is not the larger part of a twin prime pair.
1
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
1,1
COMMENTS
This is the complement of A088176 in the set of odd primes. - R. J. Mathar, Jul 04 2013
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
a(n) ~ prime(n) ~ n log n. - Charles R Greathouse IV, Jun 28 2013
EXAMPLE
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.
MATHEMATICA
Select[Prime[Range[2, 100]], Not[PrimeQ[NextPrime[#, -1] - 2]] &] (* Alonso del Arte, Jul 04 2013 *)
PROG
(PARI) is(n)=n>2 && !isprime(precprime(n-2)-2) && isprime(n) \\ Charles R Greathouse IV, Mar 18 2014
CROSSREFS
Sequence in context: A157468 A191017 A228228 * A157974 A019420 A306930
KEYWORD
nonn
AUTHOR
Irina Gerasimova, Jun 28 2013
STATUS
approved