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