A089253 - OEIS

%I #29 Feb 04 2024 01:16:33

%S 4,5,6,8,9,11,12,14,17,18,21,23,24,26,29,32,33,36,38,39,42,44,47,51,

%T 53,54,56,57,59,66,68,71,72,77,78,81,84,86,89,92,93,98,99,101,102,108,

%U 114,116,117,119,122,123,128,131,134,137,138,141,143,144,149,156,158,159,161

%N Numbers n such that 2n - 5 is a prime.

%D M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988

%D Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997

%H Shawn A. Broyles, <a href="/A089253/b089253.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A067076(n) + 4. - _Giovanni Teofilatto_, Dec 14 2003

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

%o (PARI) a(n)=prime(n+1)\2+3 \\ _Charles R Greathouse IV_, Oct 30 2012

%Y Numbers n such that 2n+k is prime: A005097 (k=1), A067076 (k=3), A089038 (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), this sequence (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 1,1

%A _Giovanni Teofilatto_, Dec 12 2003

%E Corrected by _Ralf Stephan_, Mar 03 2004

%E Further correction from _Jeremy Gardiner_, Sep 11 2004