A228172 Number of integer pairs (x,y) such that 0<=y<=x, x>0, and x^2+y^2<=n^2.

1, 3, 6, 9, 14, 19, 24, 31, 39, 48, 56, 65, 77, 88, 101, 113, 127, 141, 157, 174, 189, 208, 226, 244, 266, 287, 309, 330, 353, 378, 401, 428, 454, 482, 511, 537, 568, 596, 630, 662, 692, 726, 760, 797, 833, 867, 905, 942, 982, 1023, 1065, 1106, 1146, 1189, 1231, 1278, 1322, 1369, 1414, 1462, 1512

Offset: 1

Author

Olivier Gérard, Aug 17 2013

Keywords

• nonn

Comments

This corresponds to points of positive norm less than or equal to n on the square lattice, in the first quadrant, on or below the first diagonal.

Crossrefs

Cf. A211340 (version excluding the cases with y=0).

Formula

a(n) = A211340 (n) + n . [Joerg Arndt, Aug 19 2013]