A089038 - OEIS

%I #43 Feb 04 2024 01:15:35

%S 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,

%T 51,52,54,61,63,66,67,72,73,76,79,81,84,87,88,93,94,96,97,103,109,111,

%U 112,114,117,118,123,126,129,132,133,136,138,139,144,151,153,154,156,163

%N Nonnegative numbers k such that 2k+5 is prime.

%H Vincenzo Librandi, <a href="/A089038/b089038.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = (A086304(n-1) + 1)/2, n > 1.

%t (Prime[Range[3,100]]-5)/2 (* _Vladimir Joseph Stephan Orlovsky_, Feb 08 2010 *)

%t Select[Range[0, 200], PrimeQ[2*# + 5] &] (* _Vincenzo Librandi_, Oct 16 2012 *)

%o (Magma) [n: n in [0..200]| IsPrime(2*n+5)] // _Vincenzo Librandi_, Nov 17 2010

%o (PARI) is(n)=isprime(2*n+5) \\ _Charles R Greathouse IV_, Feb 16 2017

%o (Sage) [n for n in (0..200) if is_prime(2*n+5) ] # _G. C. Greubel_, May 21 2019

%o (GAP) Filtered([0..200], k-> IsPrime(2*k+5) ) # _G. C. Greubel_, May 21 2019

%Y Cf. A086304.

%Y 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).

%Y 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).

%K easy,nonn

%O 1,3

%A _Ray Chandler_, Nov 29 2003

%E Removed wrong comment by _Ralf Stephan_, Nov 17 2010

%E Definition clarified by _Zak Seidov_, Jul 11 2014