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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Extended to a(1)-a(2) using the formula.

LINKS

Table of n, a(n) for n=1..43.

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: A334595 A124443 A077172 * A249990 A097288 A223894

Adjacent sequences:  A160044 A160045 A160046 * A160048 A160049 A160050

KEYWORD

nonn

AUTHOR

Eric W. Weisstein, Apr 30 2009

STATUS

approved

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Last modified May 28 21:37 EDT 2020. Contains 334690 sequences. (Running on oeis4.)