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 A243154 #15 Aug 15 2021 11:44:30
%S A243154 0,0,0,0,4,0,2,0,4,0,7,0,4,0,0,4,11,0,2,0,4,7,7,0,12,4,0,0,2,9,0,0,2,
%T A243154 0,6,2,1,4,10,0,13,4,0,4,10,4,0,0,2,8,0,0,5,6,0,30,20,16,4,11,7,0,5,
%U A243154 13,0,11,18,0,2,18,5,0,1,4,5,10,4,7,4,5,11
%N A243154 Smallest k>=0 such that prime(n)*prime(n+k)-2 is prime.
%C A243154 One of the possible illustrations of Chen's theorem: there are infinitely many primes p such that p+2 is semiprime.
%C A243154 For a dual sequence, see A243158.
%t A243154 skp[n_]:=Module[{k=0,p=Prime[n]},While[!PrimeQ[p Prime[n+k]-2],k++];k]; Array[skp,90] (* _Harvey P. Dale_, Aug 15 2021 *)
%o A243154 (PARI) vector(1000, n, k=0; while(!isprime(prime(n)*prime(n+k)-2), k++); k) \\ _Colin Barker_, May 31 2014
%Y A243154 Cf. A243158.
%K A243154 nonn
%O A243154 1,5
%A A243154 _Vladimir Shevelev_, May 31 2014
%E A243154 a(25) corrected and more terms from _Colin Barker_, May 31 2014