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 A192611 #21 Mar 19 2023 05:00:21 %S A192611 2,3,7,13,89,113,151,181,359,433,521,541,641,701,719,827,953,1033, %T A192611 1277,1301,1439,1877,2069,2111,2143,2267,2357,2423,2791,2801,2861, %U A192611 2887,3191,3251,3313,3557,3643,3739,3797,3821,3863,3931,3947,4021,4447 %N A192611 Primes prime(k) such that prime(k)*k+1 is also prime. %C A192611 Primes p such that p*pi(p)+1 is prime (see Crossrefs). %H A192611 Charles R Greathouse IV, <a href="/A192611/b192611.txt">Table of n, a(n) for n = 1..10000</a> %e A192611 13 is in the list because, being the 6th prime, 13*6+1=79 is prime. %t A192611 Select[Prime[Range[700]],PrimeQ[# PrimePi[#]+1]&] (* _Harvey P. Dale_, May 28 2012 *) %o A192611 (Magma) [ NthPrime(n): n in [1..650] | IsPrime(NthPrime(n)*n+1) ]; // _Bruno Berselli_, Jul 05 2011 %o A192611 (PARI) k=0;forprime(p=2,1e4,if(isprime(k++*p+1),print1(p", "))) \\ _Charles R Greathouse IV_, Jul 05 2011 %Y A192611 Cf. A096064, A086172. %Y A192611 Cf. A000040 The prime numbers. %Y A192611 Cf. A000720 pi(n), the number of primes <= n. %K A192611 nonn %O A192611 1,1 %A A192611 _Andrea Raffetti_, Jul 05 2011