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A089038 Nonnegative numbers k such that 2k+5 is prime. 34
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
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
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

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Last modified July 20 15:46 EDT 2024. Contains 374459 sequences. (Running on oeis4.)