

A046954


Numbers n such that 6n+1 is nonprime.


11



0, 4, 8, 9, 14, 15, 19, 20, 22, 24, 28, 29, 31, 34, 36, 39, 41, 42, 43, 44, 48, 49, 50, 53, 54, 57, 59, 60, 64, 65, 67, 69, 71, 74, 75, 78, 79, 80, 82, 84, 85, 86, 88, 89, 92, 93, 94, 97, 98, 99, 104, 106, 108, 109, 111, 113, 114, 116, 117, 119, 120, 124, 127, 129, 130, 132, 133, 134, 136, 139, 140
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OFFSET

1,2


COMMENTS

A046954 = A171696 U A121763; A121765 U A171696 = A046953; A121763 U A121765 = A067611 where A067611 U A002822 U A171696 = A001477.  JuriStepan Gerasimov, Feb 13 2010, Feb 15 2010
Numbers (except 0) can be written as 6xy ±(x+y) for x>0, y>0.  Ron R Spencer, Aug 01 2016


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000


EXAMPLE

a(2)=8 because 6*8+1=49 which is composite.


MATHEMATICA

a = Flatten[Table[If[PrimeQ[6*n + 1] == False, n, {}], {n, 0, 50}]] (* Roger L. Bagula, May 17 2007 *)
Select[Range[0, 200], !PrimeQ[6 # + 1] &] (* Vincenzo Librandi, Sep 27 2013 *)


PROG

(MAGMA) /* see example triangle */ [[(2*n*k+n+k)/3: k in [1..n]]: n in [1..15]]; // Vincenzo Librandi, Sep 27 2013
(Haskell)
a046954 n = a046954_list !! (n1)
a046954_list = map (`div` 6) $ filter ((== 0) . a010051' . (+ 1)) [0, 6..]
 Reinhard Zumkeller, Jul 13 2014
(PARI) is(n)=!isprime(6*n+1) \\ Charles R Greathouse IV, Aug 01 2016


CROSSREFS

Cf. A047845 (2n+1), A045751 (4n+1), A127260 (8n+1).
Cf. A046953, A008588, A016921, subsequence of A067611.
Sequence in context: A163408 A060299 A120512 * A112775 A107747 A121763
Adjacent sequences: A046951 A046952 A046953 * A046955 A046956 A046957


KEYWORD

nonn


AUTHOR

Felice Russo


EXTENSIONS

Edited by N. J. A. Sloane, Aug 08 2008 at the suggestion of R. J. Mathar
Corrected by JuriStepan Gerasimov, Feb 13 2010, Feb 15 2010
Corrected by Vincenzo Librandi, Sep 27 2013


STATUS

approved



