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 A137753 #7 Jun 22 2013 16:06:10 %S A137753 1,1,2,1,2,1,3,1,6,5,3,1,4,1,12,7,12,7,4,1,5,1,20,9,30,31,20,9,5,1,6, %T A137753 1,30,11,60,49,60,49,30,11,6,1,7,1,42,13,105,71,140,209,105,71,42,13, %U A137753 7,1,8,1,56,15,168,97,280,351,280,351,168,97 %N A137753 First denominator and then numerator (left to right) of Leibniz's harmonic-like triangle. %e A137753 1/1; --> 1 1 %e A137753 1/2, 1/2; --> 2 1 2 1 %e A137753 1/3, 5/6, 1/3; --> 3 1 6 5 3 1 %e A137753 1/4, 7/12, 7/12, 1/4; --> 4 1 12 7 12 7 4 1 %e A137753 1/5, 9/20, 31/30, 9/20, 1/5; --> 5 1 20 9 30 31 20 9 5 1 %Y A137753 Cf. A003506; A007622; A046201; A046204; A046205; A046206; A046208; A046212; A137752. %Y A137753 Cf. A137752 %K A137753 frac,nonn,tabf,less %O A137753 1,3 %A A137753 _Mohammad K. Azarian_, Feb 10 2008