OFFSET
1,1
COMMENTS
Cousin primes are prime pairs that differ by 4. Any prime p in this sequence is such that p = (p-3)/2 + (p+5)/2 - 1, where (p-3)/2 and (p+5)/2 are also primes and they differ by 4.
Proper subset of A040117 (e.g., 5 isn't in the sequence). - David A. Corneth, Jun 24 2016
Subsequence of A072669. - Michel Marcus, Jun 27 2016
LINKS
John Cerkan, Table of n, a(n) for n = 1..10000
EXAMPLE
17 = 7 + 11 - 1. Note that, (17-3)/2 = 7 and (17+5)/2 = 11 and 7, 11 are cousin prime pairs.
29 = 13 + 17 - 1. Note that, (29-3)/2 = 13 and (29+5)/2 = 17 and 13, 17 are cousin prime pairs.
41 = 19 + 23 - 1. Note that, (41-3)/2 = 19 and (41+5)/2 = 23 and 19, 23 are cousin prime pairs.
89 = 43 + 47 - 1. Note that, (89-3)/2 = 43 and (89+5)/2 = 47 and 43, 47 are cousin prime pairs.
MATHEMATICA
Select[2 # + 3 &@ Select[Prime@ Range@ 512, PrimeQ[# + 4] &], PrimeQ] (* Michael De Vlieger, Jun 26 2016 *)
PROG
(PARI) is(n) = isprime(n) && isprime((n-3)/2) && isprime((n+5)/2) \\ David A. Corneth, Jun 24 2016
(Perl) use ntheory ":all"; say for grep{is_prime($_)} map { $_+$_+4-1 } sieve_prime_cluster(1, 5e8, 4) # Dana Jacobsen, Apr 27 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Debapriyay Mukhopadhyay, Jun 24 2016
STATUS
approved