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 A340906 Number of ways to write n as an ordered sum of 7 squares of positive integers. 10
 1, 0, 0, 7, 0, 0, 21, 0, 7, 35, 0, 42, 35, 0, 105, 28, 21, 140, 49, 105, 105, 106, 210, 84, 182, 210, 217, 287, 105, 420, 378, 126, 497, 392, 420, 532, 350, 630, 714, 434, 546, 980, 742, 609, 980, 896, 1071, 882, 875, 1470, 1239, 1099, 1155, 1722, 1652, 882, 1933, 1995, 1554, 2072, 1505 (list; graph; refs; listen; history; text; internal format)
 OFFSET 7,4 LINKS Alois P. Heinz, Table of n, a(n) for n = 7..20000 FORMULA G.f.: (theta_3(x) - 1)^7 / 128, where theta_3() is the Jacobi theta function. MAPLE b:= proc(n, t) option remember; `if`(n=0, `if`(t=0, 1, 0), `if`(t<1, 0, add((s-> `if`(s>n, 0, b(n-s, t-1)))(j^2), j=1..isqrt(n)))) end: a:= n-> b(n, 7): seq(a(n), n=7..67); # Alois P. Heinz, Jan 31 2021 MATHEMATICA nmax = 67; CoefficientList[Series[(EllipticTheta[3, 0, x] - 1)^7/128, {x, 0, nmax}], x] // Drop[#, 7] & CROSSREFS Cf. A000290, A008451, A010052, A025431, A045849, A063691, A063725, A063730, A340481, A340905, A340915, A340946, A340947. Column k=7 of A337165. Sequence in context: A211904 A094898 A341806 * A136115 A061846 A335947 Adjacent sequences: A340903 A340904 A340905 * A340907 A340908 A340909 KEYWORD nonn AUTHOR Ilya Gutkovskiy, Jan 31 2021 STATUS approved

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Last modified November 27 09:16 EST 2022. Contains 358367 sequences. (Running on oeis4.)