Voozh

A047808

a(n) counts different values of i^2 + j^2 <= n^2 or number of distances from the origin to all integer points inside a circle of radius n.

1, 2, 4, 7, 10, 14, 19, 24, 30, 37, 44, 52, 59, 69, 78, 87, 98, 109, 121, 133, 146, 158, 173, 186, 200, 216, 233, 249, 265, 283, 300, 318, 338, 357, 377, 398, 418, 439, 461, 482, 505, 528, 553, 576, 602, 626, 653, 680, 705, 735, 762, 790, 819, 847, 877, 904

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

T. D. Noe, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = number of b(i) <= n^2, b() = A001481.

MATHEMATICA

Table[ Length@Union@Flatten@Table[ i^2+j^2, {i, 0, n}, {j, 0, Min[ i, Floor[ Sqrt[ n^2-i^2 ] ] ]} ], {n, 0, 64} ]

CROSSREFS

Cf. A047809, A001481.

Sequence in context: A323623 A055607 A024512 * A007980 A022339 A025711