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 A320188 Number of integer solutions to a^2 + 2*b^2 + 3*c^2 + 7*d^2 = n. 8
 1, 2, 2, 6, 6, 4, 12, 6, 6, 18, 12, 20, 26, 28, 20, 20, 34, 4, 30, 44, 20, 48, 44, 20, 20, 38, 16, 42, 62, 40, 56, 48, 34, 24, 72, 40, 70, 112, 36, 56, 68, 44, 40, 124, 60, 60, 124, 24, 66, 62, 54, 96, 92, 80, 64, 80, 64, 88, 136, 64, 76, 140, 52, 70, 166, 44, 104, 196, 44 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n) > 0 for n >= 0. LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 FORMULA G.f.: theta_3(q) * theta_3(q^2) * theta_3(q^3) * theta_3(q^7). MATHEMATICA CoefficientList[Series[Product[EllipticTheta[3, 0, q^k], {k, 1, 3}]*EllipticTheta[3, 0, q^7], {q, 0, 80}], q] (* G. C. Greubel, Oct 29 2018 *) PROG (PARI) q='q+O('q^80); Vec(prod(k=1, 3, eta(q^(2*k))^5/(eta(q^k)* eta(q^(4*k)))^2 )*eta(q^(14))^5/(eta(q^7)* eta(q^(28)))^2 ) \\ G. C. Greubel, Oct 29 2018 CROSSREFS Cf. A320138, A320139, A320140, A033712, A320189, A320190, A320191. Sequence in context: A320191 A320190 A320189 * A033712 A033730 A033754 Adjacent sequences: A320185 A320186 A320187 * A320189 A320190 A320191 KEYWORD nonn AUTHOR Seiichi Manyama, Oct 07 2018 STATUS approved

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Last modified April 21 16:49 EDT 2024. Contains 371874 sequences. (Running on oeis4.)