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 A137762 #9 Jun 22 2013 16:06:10 %S A137762 1,1,5,6,31,30,209,140,1471,630,10625,2772 %N A137762 Central elements in writing first the numerator and then the denominator (left to right) of Leibniz's harmonic-like triangle. %F A137762 a(2n-1)=A137763(2n); a(2n)=A137763(2n-1)=A046212(2n-1)=A056040(2n-1)=A100071(2n-1). - M. F. Hasler, Jan 25 2012 %e A137762 1/1; --> 1 1 %e A137762 1/2, 1/2; --> %e A137762 1/3, 5/6, 1/3; --> 5 6 %e A137762 1/4, 7/12, 7/12, 1/4; --> ... %e A137762 1/5, 9/20, 31/30, 9/20, 1/5; %Y A137762 Cf. A046201; A046204; A046205; A046206; A046208; A046212; A137752; A137753; A137754; A137755; A137756; A137757; A137758; A137759, A137760; A137761. %K A137762 nonn,tabf,frac %O A137762 1,3 %A A137762 _Mohammad K. Azarian_, Feb 13 2008