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 A137761 #7 Jun 22 2013 16:06:10 %S A137761 1,2,3,6,5,4,12,7,20,9,30,31,11,60,49,42,13,105,71,140,209,8,56,15, %T A137761 168,97,280,351,72,17,252,127,504,545,630,1471,10,90,19,360,161,840, %U A137761 799,1260,2561,110,21,495,199,1320,1121,2310,4159,2772,10625 %N A137761 Distinct numbers in writing first denominator and then numerator (left to right) of Leibniz's harmonic-like triangle. %e A137761 1/1; --> 1 %e A137761 1/2, 1/2; --> 2 %e A137761 1/3, 5/6, 1/3; --> 3 6 5 %e A137761 1/4, 7/12, 7/12, 1/4; %e A137761 1/5, 9/20, 31/30, 9/20, 1/5; %Y A137761 Cf. A046201; A046204; A046205; A046206; A046208; A046212; A137752; A137753; A137754; A137755; A137756; A137757; A137758; A137759, A137760. %K A137761 frac,nonn,tabf,less %O A137761 1,2 %A A137761 _Mohammad K. Azarian_, Feb 11 2008