A089038 Nonnegative numbers k such that 2k+5 is prime.

0, 1, 3, 4, 6, 7, 9, 12, 13, 16, 18, 19, 21, 24, 27, 28, 31, 33, 34, 37, 39, 42, 46, 48, 49, 51, 52, 54, 61, 63, 66, 67, 72, 73, 76, 79, 81, 84, 87, 88, 93, 94, 96, 97, 103, 109, 111, 112, 114, 117, 118, 123, 126, 129, 132, 133, 136, 138, 139, 144, 151, 153, 154, 156, 163

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).

Numbers n such that 2n-k is prime: A006254 (k=1), A098090 (k=3), A089253 (k=5), A089192 (k=7), A097069 (k=9), A097338 (k=11), A097363 (k=13), A097480 (k=15), A098605 (k=17), A097932 (k=19).

Sequence in context: A360799 A136110 A032725 * A336175 A137673 A226245

Adjacent sequences: A089035 A089036 A089037 * A089039 A089040 A089041

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