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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. 3
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

Adjacent sequences:  A047805 A047806 A047807 * A047809 A047810 A047811

KEYWORD

nonn,easy,nice

AUTHOR

Wouter Meeussen, David W. Wilson

STATUS

approved

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Last modified October 15 10:15 EDT 2019. Contains 328026 sequences. (Running on oeis4.)