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%I #15 Sep 20 2019 19:35:29
%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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