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 A020939 #6 Jan 10 2013 17:22:11
%S A020939 7,9,14,18,25,30,36,39,46,55,59,67,73,76,82,91,99,101,110,115,119,127,
%T A020939 132,139,150,155,157,162,165,170,189,193,202,204,217,217,223,232,239,
%U A020939 245,254,258,267,270,274,278,290,304,309,310,316,324,326,335,344,350
%N A020939 Greatest k such that (k-th prime) < (9 times n-th prime).
%H A020939 Harvey P. Dale, <a href="/A020939/b020939.txt">Table of n, a(n) for n = 1..1000</a>
%t A020939 Table[PrimePi[NextPrime[9*Prime[n],-1]],{n,60}] (* _Harvey P. Dale_, Jan 10 2013 *)
%Y A020939 Cf. A020900, A020901, A020934-A020940.
%K A020939 nonn
%O A020939 1,1
%A A020939 _Clark Kimberling_
%E A020939 More terms from _Henry Bottomley_, Nov 13 2000