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 A051132 Number of ordered pairs of integers (x,y) with x^2+y^2 < n^2. 10
 0, 1, 9, 25, 45, 69, 109, 145, 193, 249, 305, 373, 437, 517, 609, 697, 793, 889, 1005, 1125, 1245, 1369, 1513, 1649, 1789, 1941, 2109, 2285, 2449, 2617, 2809, 2997, 3205, 3405, 3613, 3841, 4049, 4281, 4509, 4765, 5013, 5249, 5521, 5785, 6073, 6349, 6621 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(n) = A000328(n) - A046109(n). [Reinhard Zumkeller, Jan 23 2012] LINKS T. D. Noe, Table of n, a(n) for n = 0..1000 EXAMPLE a(3)=25 from the points of shapes 00 (1), 10 (4), 11 (4), 20 (4), 21 (8), 22 (4). MATHEMATICA Table[Sum[SquaresR[2, k], {k, 0, n^2 - 1}], {n, 0, 46}] PROG (Haskell) a051132 n = length [(x, y) | x <- [-n..n], y <- [-n..n], x^2 + y^2 < n^2] -- Reinhard Zumkeller, Jan 23 2012 CROSSREFS Changing "<" to "<=" in the definition gives A000328. Sequence in context: A031036 A348749 A291259 * A247687 A075026 A339727 Adjacent sequences: A051129 A051130 A051131 * A051133 A051134 A051135 KEYWORD nonn,nice,easy AUTHOR Jostein Trondal (jostein.trondal(AT)protech.no) EXTENSIONS More terms from James A. Sellers STATUS approved

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Last modified December 7 19:19 EST 2022. Contains 358669 sequences. (Running on oeis4.)