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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 G. C. Greubel, Table of n, a(n) for n = 1..10000 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 A102974 Adjacent sequences:  A121762 A121763 A121764 * A121766 A121767 A121768 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 25 10:01 EDT 2020. Contains 334592 sequences. (Running on oeis4.)