OFFSET
1,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = (A086304(n-1) + 1)/2, n > 1.
MATHEMATICA
(Prime[Range[3, 100]]-5)/2 (* Vladimir Joseph Stephan Orlovsky, Feb 08 2010 *)
Select[Range[0, 200], PrimeQ[2*# + 5] &] (* Vincenzo Librandi, Oct 16 2012 *)
PROG
(Magma) [n: n in [0..200]| IsPrime(2*n+5)] // Vincenzo Librandi, Nov 17 2010
(PARI) is(n)=isprime(2*n+5) \\ Charles R Greathouse IV, Feb 16 2017
(Sage) [n for n in (0..200) if is_prime(2*n+5) ] # G. C. Greubel, May 21 2019
(GAP) Filtered([0..200], k-> IsPrime(2*k+5) ) # G. C. Greubel, May 21 2019
CROSSREFS
Cf. A086304.
Numbers n such that 2n+k is prime: A005097 (k=1), A067076 (k=3), this seq (k=5), A105760 (k=7), A155722 (k=9), A101448 (k=11), A153081 (k=13), A089559 (k=15), A173059 (k=17), A153143 (k=19).
KEYWORD
easy,nonn
AUTHOR
Ray Chandler, Nov 29 2003
EXTENSIONS
Removed wrong comment by Ralf Stephan, Nov 17 2010
Definition clarified by Zak Seidov, Jul 11 2014
STATUS
approved