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 A112540 Numbers n such that (15n-4; 15n-2; 15n+2; 15n+4) is a prime quadruplet. 4
 1, 7, 13, 55, 99, 125, 139, 217, 231, 377, 629, 867, 1043, 1049, 1071, 1203, 1261, 1295, 1401, 1485, 1687, 2115, 2323, 2919, 3423, 3689, 4199, 4481, 4633, 4815, 5151, 5313, 5403, 5515, 5921, 6523, 6609, 6741, 7323, 7769, 7953, 8147, 9031, 9611, 10485, 11047 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Also (4p + 16)/60 such that (p, p + 2, p + 6 and p + 8) is a prime quadruplet for p >= 11. - Michel Lagneau, Jul 02 2012 The density of these four-prime groups is approximately equal to (log x)^-3.45 (but not (log x)^-4). - Xueshi Gao, Jun 01 2014 All of the terms of this sequence are either 1, 7 or 13 modulo 14. - Rodolfo Ruiz-Huidobro, Dec 27 2019 LINKS Dana Jacobsen, Table of n, a(n) for n = 1..10000 EXAMPLE n = 7 => 15 * 7 - 4 = 101, 15 * 7 - 2 = 103, 15 * 7 + 2 = 107, 15 * 7 + 4 = 109. MAPLE A112540:=n->`if`(isprime(15*n-4) and isprime(15*n-2) and isprime(15*n+2) and isprime(15*n+4), n, NULL); seq(A112540(n), n=1..20000); # Wesley Ivan Hurt, Jul 26 2014 MATHEMATICA Select[Range[6610], PrimeQ[15# - 4] && PrimeQ[15# - 2] && PrimeQ[15# + 2] && PrimeQ[15# + 4]&] (* T. D. Noe, Nov 16 2006 *) PROG (PARI) for(n=1, 1e4, if(isprime(15*n-4) && isprime(15*n-2) && isprime(15*n+2) && isprime(15*n+4), print1(n, ", "))) \\ Felix FrÃ¶hlich, Jul 26 2014 (Perl) use ntheory ":all"; say for map { (4*\$_+16)/60 } sieve_prime_cluster(11, 15*10000, 2, 6, 8); # Dana Jacobsen, Dec 15 2015 (MAGMA) [n: n in [0..2*10^4] | IsPrime(15*n-4) and IsPrime(15*n-2) and IsPrime(15*n+2) and IsPrime(15*n+4)]; // Vincenzo Librandi, Dec 28 2015 CROSSREFS Cf. A007530, A014561. Sequence in context: A320462 A108056 A018562 * A193489 A091005 A015441 Adjacent sequences:  A112537 A112538 A112539 * A112541 A112542 A112543 KEYWORD nonn,easy AUTHOR Karsten Meyer, Dec 16 2005 EXTENSIONS Corrected by T. D. Noe, Nov 16 2006 STATUS approved

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Last modified October 24 07:04 EDT 2020. Contains 337975 sequences. (Running on oeis4.)