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%I #13 Dec 07 2017 22:14:08
%S 1,1,1,1,2,1,6,3,4,6,60,5,20,10,28,35,280,140,2520,126,120,1260,27720,
%T 1155,5544,13860,40040,12870,360360,12012,360360,45045,21840,360360,
%U 350064,340340,4084080,2042040,1989680,1939938,15519504,369512,5173168
%N Denominator of the Harary number for the cycle graph C_n.
%C Extended to a(1)-a(2) using the formula.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/HararyIndex.html">Harary Index</a>
%e 0, 1, 3, 5, 15/2, 10, 77/6, 47/3, 75/4, 131/6, ...
%t Denominator[Table[1 - Mod[n, 2] + n HarmonicNumber[Floor[(n - 1)/2]], {n, 43}]] (* _Eric W. Weisstein_, Dec 06 2017 *)
%Y Cf. A160046.
%K nonn
%O 1,5
%A _Eric W. Weisstein_, Apr 30 2009