

A053456


Open disk numbers (version 1): a(n) is the number of points (i,j), i,j, integers, contained in an 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
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OFFSET

0,4


LINKS



FORMULA

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


CROSSREFS



KEYWORD

easy,nonn


AUTHOR

Klaus Strassburger (strass(AT)ddfi.uniduesseldorf.de), Jan 13 2000


STATUS

approved



