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A160047
Denominator of the Harary number for the cycle graph C_n.
1
1, 1, 1, 1, 2, 1, 6, 3, 4, 6, 60, 5, 20, 10, 28, 35, 280, 140, 2520, 126, 120, 1260, 27720, 1155, 5544, 13860, 40040, 12870, 360360, 12012, 360360, 45045, 21840, 360360, 350064, 340340, 4084080, 2042040, 1989680, 1939938, 15519504, 369512, 5173168
OFFSET
1,5
COMMENTS
Extended to a(1)-a(2) using the formula.
LINKS
Eric Weisstein's World of Mathematics, Harary Index
EXAMPLE
0, 1, 3, 5, 15/2, 10, 77/6, 47/3, 75/4, 131/6, ...
MATHEMATICA
Denominator[Table[1 - Mod[n, 2] + n HarmonicNumber[Floor[(n - 1)/2]], {n, 43}]] (* Eric W. Weisstein, Dec 06 2017 *)
CROSSREFS
Cf. A160046.
Sequence in context: A350684 A124443 A077172 * A249990 A097288 A223894
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Apr 30 2009
STATUS
approved