login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A088899 T(n,k) = number of ordered pairs of integers (x,y) with x^2/n^2 + y^2/k^2 = 1, 1<=k<=n; triangular array, read by rows. 2
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 12, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 12, 4, 4, 4, 4, 12, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 12, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

T(n,k) = number of lattice points on the circumference of an ellipse with semimajor axis = n, semiminor axis = k and center = (0,0).

a(n) = A088897(n) - A088898(n);

T(n,n) = A046109(n).

LINKS

Table of n, a(n) for n=1..101.

Eric Weisstein's World of Mathematics, Ellipse

CROSSREFS

Sequence in context: A138908 A032564 A141248 * A066014 A080678 A096300

Adjacent sequences:  A088896 A088897 A088898 * A088900 A088901 A088902

KEYWORD

nonn,tabl

AUTHOR

Reinhard Zumkeller, Oct 21 2003

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified November 28 07:52 EST 2014. Contains 250285 sequences.