A053457 - OEIS

%I #8 Mar 23 2022 12:18:09

%S 0,0,2,6,12,16,26,38,48,60,78,94,108,128,154,174,196,224,250,278,312,

%T 344,378,410,452,484,526,574,612,652,698,754,800,848,906,958,1012,

%U 1068,1130,1190,1252,1316,1378,1446,1516,1588,1654,1730,1808,1880,1954

%N Open disk numbers (version 2): a(n) is the number of points (i,j), i,j, integers, contained in an open disk of diameter n, centered at (0,1/2).

%C a(n)/(n/2)^2->Pi

%Y Cf. A053414, A053456, A053458, A053459.

%K easy,nonn

%O 0,3

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