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 A228857 #21 Feb 03 2024 00:54:24 %S A228857 5,17,47,53,59,83,107,113,149,167,173,239,269,353,419,443,449,503,509, %T A228857 563,587,599,647,659,677,719,797,827,929,947,977,983,1097,1103,1109, %U A228857 1187,1193,1223,1229,1259,1289,1367,1409,1427,1433,1439,1493,1523,1667 %N A228857 Odd primes p > 3 for which 14*p+1 is also prime. %C A228857 In 1823, Legendre proved that the first case of Fermat’s Last Theorem is true for all exponents that are members of this sequence (see Ribenboim’s reference, p.112). %D A228857 Paulo Ribenboim; Fermat’s Last Theorem For Amateurs, Springer-Verlag, New York, Inc., (1999). %e A228857 As both 5 and 14*5 + 1 = 71 are prime, then 5 is a member of this sequence. %t A228857 Select[Prime[Range[3,1667]],PrimeQ[14#+1] &] %o A228857 (Magma) [p: p in PrimesInInterval(5,2000) |IsPrime(14*p+1)]; // _Vincenzo Librandi_, Sep 18 2016 %o A228857 (PARI) lista(nn) = forprime(p=5, nn, if(isprime(14*p+1), print1(p, ", "))); \\ _Altug Alkan_, Sep 18 2016 %Y A228857 Cf. A005384, A023212, A023228, A023237, A155943. %K A228857 nonn %O A228857 1,1 %A A228857 _Ant King_, Sep 06 2013