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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 * A258199 A066014 A080678

Adjacent sequences:  A088896 A088897 A088898 * A088900 A088901 A088902

KEYWORD

nonn,tabl

AUTHOR

Reinhard Zumkeller, Oct 21 2003

STATUS

approved

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Last modified August 29 03:27 EDT 2015. Contains 261184 sequences.