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A121765 Numbers n such that 6*n-1 is composite while 6*n+1 is prime. 8
6, 11, 13, 16, 21, 26, 27, 35, 37, 46, 51, 55, 56, 61, 62, 63, 66, 68, 73, 76, 81, 83, 90, 91, 96, 101, 102, 105, 112, 115, 118, 121, 122, 123, 125, 126, 128, 131, 142, 146, 151, 153, 156, 161, 165, 166, 168, 173, 178, 181, 186, 187, 188, 195, 200, 202, 206, 208, 216 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Entries in A046953 which are not in A060461 or equivalently, entries in A024899 which are not in A002822.
LINKS
MATHEMATICA
Select[Range[250], ! 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] | not IsPrime(6*n-1) and IsPrime(6*n+1)]; // G. C. Greubel, Feb 20 2019
(Sage)[n for n in (1..250) if not is_prime(6*n-1) and is_prime(6*n+1)] # G. C. Greubel, Feb 20 2019
(GAP) Filtered([1..250], k-> not IsPrime(6*k-1) and IsPrime(6*k+1)) # G. C. Greubel, Feb 20 2019
CROSSREFS
Cf. A121764.
Sequence in context: A175021 A315367 A046953 * A315368 A315369 A350675
KEYWORD
nonn
AUTHOR
Lekraj Beedassy, Aug 20 2006
EXTENSIONS
Extended by Ray Chandler, Aug 22 2006
STATUS
approved

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Last modified May 27 11:46 EDT 2024. Contains 372858 sequences. (Running on oeis4.)