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A171696 Nonnegative numbers k such that neither 6*k+-1 is prime. 8
0, 20, 24, 31, 34, 36, 41, 48, 50, 54, 57, 69, 71, 79, 86, 88, 89, 92, 97, 104, 106, 111, 116, 119, 130, 132, 134, 136, 139, 141, 145, 149, 150, 154, 160, 167, 171, 174, 176, 179, 180, 189, 190, 191, 193, 196, 201, 207, 209, 211, 212, 219, 222, 223, 224, 225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A060461 is the main sequence for this entry.

Numbers k such that 6*k-1 and 6*k+1 are twin nonprimes.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

a(n+1) = A060461(n).

a(n) = n + O(n/log n). - Charles R Greathouse IV, Feb 17 2017

MAPLE

isA171696 := proc(n) not isprime(6*n+1) and not isprime(6*n-1) ; end proc: for n from 0 to 300 do if isA171696(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Mar 18 2010

MATHEMATICA

Select[Range[0, 225], !Or @@ PrimeQ[6# + {-1, 1}] &] (* Amiram Eldar, Jan 21 2020 *)

PROG

(PARI) is(n)=!isprime(6*n-1) && !isprime(6*n+1) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A001477, A060461.

Sequence in context: A221651 A108373 A109131 * A060461 A214177 A044996

Adjacent sequences:  A171693 A171694 A171695 * A171697 A171698 A171699

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Dec 15 2009

STATUS

approved

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Last modified August 13 02:09 EDT 2020. Contains 336441 sequences. (Running on oeis4.)