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 A071576 #17 Oct 19 2017 03:14:03
%S A071576 1,1,1,165,5415,12705,256410,256410,6480303060,217245863835,
%T A071576 946622690475,35511547806735,439116128090640,5714676453270219435
%N A071576 a(n) = least k such that 2ik + 1 is prime for all 1 <= i <= n.
%t A071576 k = 1; Do[ While[p = Table[2*i*k + 1, {i, 1, n}]; Union[ PrimeQ[p]] != {True}, k++ ]; Print[k], {n, 1, 15}] (* _Robert G. Wilson v_ *)
%o A071576 (PARI) for(n=1,6,s=1; while(sum(i=1,n,isprime(2*s*i+1))<n,s++); print1(s,","))
%Y A071576 Cf. A088250, A124516, A124522, A124522, A063983.
%Y A071576 Cf. A005097, A123998, A124408-A124411.
%K A071576 more,nonn
%O A071576 1,4
%A A071576 _Benoit Cloitre_, May 31 2002
%E A071576 Extended by _Robert G. Wilson v_, Jun 06 2002
%E A071576 a(9) from _Ryan Propper_, Jun 20 2005
%E A071576 a(10)-a(13) from _Don Reble_, Nov 05 2006
%E A071576 a(14) from _Giovanni Resta_, Apr 01 2017