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 A090835 Numbers n such that if p=prime(n), then p, p+6, p+12, p+18 are consecutive primes with p=6*k+5 for some k, where prime(n) denotes n-th prime. 8

%I

%S 54,709,821,1510,1594,1726,1842,2009,2600,2876,5689,6252,7438,7728,

%T 8090,8229,8654,9105,9184,9997,10934,11343,11390,14193,14866,15000,

%U 16320,16748,16950,17246,18466,19164,19802,20152,21508,21692,22048,22270,22997,23242,25435,25466

%N Numbers n such that if p=prime(n), then p, p+6, p+12, p+18 are consecutive primes with p=6*k+5 for some k, where prime(n) denotes n-th prime.

%e prime(54) = 251: 251, 257, 263, 269 are consecutive primes.

%t PrimePi/@Transpose[Select[Partition[Prime[Range[50000]],4,1],Differences[#]=={6, 6, 6}&&Mod[#[[1]],6]==5&]][[1]] (* _Metin Sariyar_, Sep 21 2019 *)

%o (PARI) isok(n) = {my(p=prime(n), q, r, s); ((p % 6) == 5) && ((q=nextprime(p+1)) == p+6) && ((r=nextprime(q+1)) == p+12) && ((s=nextprime(r+1)) == p+18);} \\ _Michel Marcus_, Sep 20 2019

%Y Cf. A000040, A033451, A090832, A090833, A090834, A090836, A090837, A090838, A090839.

%K easy,nonn

%O 1,1

%A _Pierre CAMI_, Dec 09 2003

%E a(9) corrected and more terms from _Michel Marcus_, Sep 20 2019

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Last modified April 23 10:07 EDT 2021. Contains 343204 sequences. (Running on oeis4.)