This site is supported by donations to The OEIS Foundation.



Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A063837 Divisibility tournaments with odd determinants. 0
44, 46, 48, 50, 51, 52, 68, 69, 77, 81, 86, 87, 93, 99, 100, 108, 110, 118, 126, 130 (list; graph; refs; listen; history; text; internal format)



Let n be a positive integer, n>3. Define a tournament on the vertex set {2,3,...n} by: for i< j, i is adjacent to j if i divides j, else, j is adjacent to i and let T(n) be its adjacency matrix. It appears that values of n for which det(T(n)) is odd are rather sparse. Shown above are the n in the range 4...130 for which det(T(n)) is odd.


Table of n, a(n) for n=0..19.


Cf. A057980.

Sequence in context: A225619 A121610 A254752 * A178755 A182261 A061757

Adjacent sequences:  A063834 A063835 A063836 * A063838 A063839 A063840




Rebecca A. Winslow (raw5(AT)students.uwf.edu), Aug 21 2001



Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 15 00:30 EST 2019. Contains 329988 sequences. (Running on oeis4.)