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 A051645 #22 Feb 24 2025 02:03:01 %S A051645 2,5,7,11,19,23,41,43,61,67,71,79,89,109,113,131,137,167,181,193,223, %T A051645 229,233,277,281,313,317,331,337,359,383,439,443,457,461,467,491,503, %U A051645 509,541,547,593,599,607,641,691,701,733,739,743,751,769,797,821,823 %N A051645 Primes p such that 30*p+1 is also prime. %C A051645 A002110(3)*p+1 and p are primes. %H A051645 Amiram Eldar, <a href="/A051645/b051645.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Vincenzo Librandi) %F A051645 a(n) = (A051646(n)-1)/30. - _Amiram Eldar_, Feb 24 2025 %e A051645 p = 19 is in the sequence because 30*p+1 = 571 is also prime. %t A051645 Select[Prime[Range[900]], PrimeQ[30 # + 1] &] (* _Vincenzo Librandi_, Apr 11 2013 *) %o A051645 (Magma) [p: p in PrimesUpTo(900) | IsPrime(30*p+1)]; // _Vincenzo Librandi_, Apr 11 2013 %o A051645 (PARI) isok(k) = isprime(k) && isprime(30*k+1); \\ _Amiram Eldar_, Feb 24 2025 %Y A051645 Cf. A002110, A005384, A005385, A007693, A051646. %K A051645 nonn,easy %O A051645 1,1 %A A051645 _Labos Elemer_