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A121763 Numbers n such that 6*n-1 is prime while 6*n+1 is composite. 7
4, 8, 9, 14, 15, 19, 22, 28, 29, 39, 42, 43, 44, 49, 53, 59, 60, 64, 65, 67, 74, 75, 78, 80, 82, 84, 85, 93, 94, 98, 99, 108, 109, 113, 114, 117, 120, 124, 127, 129, 133, 140, 144, 148, 152, 155, 157, 158, 159, 162, 163, 164, 169, 183, 184, 185, 194, 197, 198, 199 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Entries of A024898 which are not in A002822 or equivalently, entries of A046954 which are not in A060461.

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[200], PrimeQ[6# -1] && !PrimeQ[6# +1] &] (* Ray Chandler, Aug 22 2006 *)

PROG

(PARI) for(n=1, 250, if(isprime(6*n-1) && !isprime(6*n+1), print1(n", "))) \\ G. C. Greubel, Feb 20 2019

(MAGMA) [n: n in [1..250] | IsPrime(6*n-1) and not IsPrime(6*n+1)]; // G. C. Greubel, Feb 20 2019

(Sage)[n for n in (1..250) if is_prime(6*n-1) and not is_prime(6*n+1)] # G. C. Greubel, Feb 20 2019

(GAP) Filtered([1..250], k-> IsPrime(6*k-1) and not IsPrime(6*k+1)) # G. C. Greubel, Feb 20 2019

CROSSREFS

Cf. A121762, A121765.

Sequence in context: A046954 A112775 A107747 * A110087 A312830 A312831

Adjacent sequences:  A121760 A121761 A121762 * A121764 A121765 A121766

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Aug 20 2006

EXTENSIONS

Extended by Ray Chandler, Aug 22 2006

STATUS

approved

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Last modified June 6 14:04 EDT 2020. Contains 334827 sequences. (Running on oeis4.)