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 A341428 Number of positive solutions to (x_1)^2 + (x_2)^2 + ... + (x_9)^2 <= n^2. 7
 1, 46, 760, 7751, 43910, 186098, 652710, 1943742, 5178030, 12411211, 27773308, 57798904, 114152429, 214399664, 387571706, 673189698, 1135916808, 1857320784, 2966816950, 4623984661, 7066527283, 10577150039, 15589368584, 22580091614, 32256768126 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,2 LINKS Alois P. Heinz, Table of n, a(n) for n = 3..1000 Index entries for sequences related to sums of squares FORMULA a(n) is the coefficient of x^(n^2) in expansion of (theta_3(x) - 1)^9 / (512 * (1 - x)). MAPLE b:= proc(n, k) option remember; `if`(k=0, 1, `if`(n=0, 0, add((s->`if`(s>n, 0, b(n-s, k-1)))(j^2), j=1..isqrt(n)))) end: a:= n-> b(n^2, 9): seq(a(n), n=3..27); # Alois P. Heinz, Feb 11 2021 MATHEMATICA Table[SeriesCoefficient[(EllipticTheta[3, 0, x] - 1)^9/(512 (1 - x)), {x, 0, n^2}], {n, 3, 27}] CROSSREFS Cf. A000122, A001182, A055408, A055415, A253663, A302995, A340946, A341398, A341404, A341423, A341424, A341425, A341426, A341427, A341429. Sequence in context: A224306 A224370 A078156 * A066405 A113922 A160067 Adjacent sequences: A341425 A341426 A341427 * A341429 A341430 A341431 KEYWORD nonn AUTHOR Ilya Gutkovskiy, Feb 11 2021 STATUS approved

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Last modified July 13 17:35 EDT 2024. Contains 374284 sequences. (Running on oeis4.)