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 A077770 Number of ordered pairs of integers (x,y) with n^2 < x^2 + y^2 < (n+1)^2; number of lattice points between circles of radii n and n+1. 4
 0, 4, 12, 16, 20, 28, 32, 44, 52, 52, 56, 60, 76, 80, 84, 84, 92, 104, 116, 116, 112, 140, 132, 136, 148, 148, 164, 160, 164, 180, 176, 204, 196, 204, 216, 196, 228, 216, 252, 236, 224, 260, 260, 284, 272, 260, 292, 288, 308, 300, 316, 312, 300, 332, 320, 364 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Note that 2*A077768(n)-a(n)/4 is the characteristic sequence for the Beatty sequence A001951(n). LINKS Eric Weisstein's World of Mathematics, Gauss's Circle Problem FORMULA a(n) = A051132(n+1) - A000328(n) MATHEMATICA Table[Sum[SquaresR[2, k], {k, n^2 + 1, (n + 1)^2 - 1}], {n, 0, 100}] CROSSREFS Cf. A000328, A001951, A051132, A077768. Sequence in context: A342090 A310565 A267958 * A310566 A108269 A081523 Adjacent sequences:  A077767 A077768 A077769 * A077771 A077772 A077773 KEYWORD nonn AUTHOR T. D. Noe, Nov 20 2002 STATUS approved

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Last modified July 30 07:55 EDT 2021. Contains 346348 sequences. (Running on oeis4.)