This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A309871 #15 Feb 29 2020 18:00:45 %S A309871 892,2432,156817,806697,822937,1377022,1389412,1418007,1619642, %T A309871 1753552,2017732,2058647,2329302,2554142,2703347,3058772,3135107, %U A309871 3326522,3391797,3723457,4126867,4132782,4171422,4411837,4610252,6378487,6440087,6878987,6897782,6991547 %N A309871 Numbers n for which 18n+1, 18n+5, 18n+7, 18n+11, 18n+13 and 18n+17 are primes. %H A309871 Ely Golden, <a href="/A309871/b309871.txt">Table of n, a(n) for n = 1..1001</a> %t A309871 tot[n_] := Select[Range[n], CoprimeQ[#, n] &]; m = 18; t = tot[m]; aQ[n_] := AllTrue[m * n + t, PrimeQ]; Select[Range[10^6], aQ] (* _Amiram Eldar_, Aug 22 2019 *) %o A309871 (SageMath) %o A309871 x = 1 %o A309871 for i in range(5000000): %o A309871 if (18*i+1 in Primes() %o A309871 and 18*i+5 in Primes() %o A309871 and 18*i+7 in Primes() %o A309871 and 18*i+11 in Primes() %o A309871 and 18*i+13 in Primes() %o A309871 and 18*i+17 in Primes()): %o A309871 print(str(x)+" "+str(i)) %o A309871 x += 1 %Y A309871 Cf. A123986, A056956, A007811, A123985. %K A309871 nonn %O A309871 1,1 %A A309871 _Ely Golden_, Aug 21 2019