The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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