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 A108013 #17 Sep 08 2022 08:45:19 %S A108013 3,5,149,179,239,269,419,569,1289,1319,2309,2549,2729,3359,3389,4259, %T A108013 4649,5849,5879,6359,6779,8999,9239,9629,10529,10889,11969,13679, %U A108013 13829,14009,14549,16229,16649,18059,18119,18539,19139,19379,21599,21839 %N A108013 Primes p such that p + 2 and p*(p + 2) + 2 are primes. %C A108013 Except for the first 2 terms, these numbers all end in 9. Proof: Any odd prime p>5 can have one of the following forms: 10k+1, 10k+3, 10k+7, 10k+9. %C A108013 10k+1 => p(p+2)+2 ends in 5, hence not prime, so p <> form 10k+1. %C A108013 10k+3 => (p+2) ends in 5, hence not prime, so p <> form 10k+3. %C A108013 10k+7 => p(p+2)+2 ends in 5, hence not prime, so p <> form 10k+7. %C A108013 Thus p is of the form 10k+9 as stated. Moreover, p+2 ends in 1 and p(p+2)+2 is of the form 100h+1 since (10k+9)(10k+11)+2 = 100(k^2+2k+1)+1. %C A108013 Subsequence of A051507. All terms larger than 5 are congruent to 29 mod 30. - _Zak Seidov_ %H A108013 Michael De Vlieger, <a href="/A108013/b108013.txt">Table of n, a(n) for n = 1..5000</a> %e A108013 149*151 + 2 = 22501. 149, 151, and 22501 are all prime so 149 is in the sequence. %t A108013 Select[Prime@ Range@ 3000, AllTrue[{#2, #1 #2 + 2}, PrimeQ] & @@ {#, # + 2} &] (* _Michael De Vlieger_, Jan 22 2018 *) %o A108013 (PARI) g(n,k) = forprime(x1=3,n, x2=x1+2; if(isprime(x2), p=x1*x2+k; if(isprime(p), print1(x1",") ) ) ) %o A108013 (Magma) [p: p in PrimesUpTo(25000)| IsPrime(p+2) and IsPrime(p^2+2*p+2)] // _Vincenzo Librandi_, Jan 29 2011 %Y A108013 Cf. A051779. %K A108013 easy,nonn %O A108013 1,1 %A A108013 _Cino Hilliard_, May 30 2005