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A053456 Open disk numbers (version 1): a(n)= number of points (i,j), i,j, integers, contained in a open disk of diameter n, centered at (0,0). 3
0, 1, 1, 9, 9, 21, 25, 37, 45, 69, 69, 97, 109, 137, 145, 177, 193, 225, 249, 293, 305, 349, 373, 421, 437, 489, 517, 577, 609, 665, 697, 749, 793, 861, 889, 973, 1005, 1085, 1125, 1201, 1245, 1313, 1369, 1457, 1513, 1597, 1649, 1741, 1789, 1885, 1941 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..50.

FORMULA

a(n)/(n/2)^2->Pi.

CROSSREFS

Cf. A053411, A053457, A053458, A053459.

Bisections: A051132, A036704.

Cf. A000796 (Pi).

Sequence in context: A161365 A214831 A197497 * A144424 A282269 A205380

Adjacent sequences:  A053453 A053454 A053455 * A053457 A053458 A053459

KEYWORD

easy,nonn

AUTHOR

Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Jan 13 2000

STATUS

approved

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Last modified January 26 15:18 EST 2022. Contains 350599 sequences. (Running on oeis4.)