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 A137722 #4 Mar 30 2012 18:50:59 %S A137722 0,0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,2,2,3,4,5,5,5,5,6,6,7,7,7,7,7,8,9, %T A137722 9,9,9,10,11,12,12,13,13,14,14,15,15,15,15,16,17,18,18,18,19,20,21,22, %U A137722 22,22,22,23,24,24,25,26,26,27,28,29,29,29,29,30,30,31,31,32,32,33,33,34 %N A137722 Number of numbers not greater than n with exactly one prime gap in their factorization. %C A137722 a(n) > a(n-1) iff A073490(n) = 1; %C A137722 A137721(n) > a(n) for n < 134; %C A137722 A137721(n) < a(n) for n > 140. %H A137722 R. Zumkeller, <a href="/A137722/b137722.txt">Table of n, a(n) for n = 1..1000</a> %Y A137722 Cf. A073493. %K A137722 nonn %O A137722 1,14 %A A137722 _Reinhard Zumkeller_, Feb 09 2008