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 A087723 #11 May 15 2013 08:38:43
%S A087723 1,2,7,11,12,13,15,19,26,29,33,35,41,48,54,71,72,76,84,86,90,92,93,96,
%T A087723 98,103,105,108,117,122,127,129,130,137,142,152,157,158,165,176,180,
%U A087723 183,191,193,194,196,213,214,218,219,229,231,233,234,235,246,250,256,267
%N A087723 Values that appear more than once in A087724 (related to the growth of PrimePi).
%t A087723 Digits=1000 a[n_]=-PrimePi[n]+Floor[Prime[n]/Log[n]]-2 b=Table[a[n], {n, 2, Digits}] c=Table[If[b[[n]]-b[[n-1]]==0, b[[n]], 0], {n, 2, Digits-1}] d=Delete[Union[c], 1]
%K A087723 nonn
%O A087723 1,2
%A A087723 _Roger L. Bagula_, Sep 29 2003