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 A107502 Theta series of quadratic form with Gram matrix [ 4, 1, 0, -1; 1, 10, 0, 3; 0, 0, 26, 13; -1, 3, 13, 36]. 6
 1, 0, 2, 0, 0, 2, 2, 0, 4, 0, 0, 2, 0, 2, 0, 6, 0, 0, 10, 8, 14, 12, 0, 0, 20, 0, 6, 0, 16, 0, 0, 8, 18, 18, 12, 0, 0, 12, 0, 8, 0, 6, 0, 0, 30, 22, 20, 10, 0, 0, 22, 0, 14, 0, 38, 0, 0, 22, 30, 18, 48, 0, 0, 30, 0, 12, 0, 22, 0, 0, 38, 16, 50, 30, 0, 0, 46, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS G.f. is theta_6 in the Parry 1979 reference on page 166. This theta series is an element of the space of modular forms on Gamma_0(169) of weight 2 and dimension 21. - Andy Huchala, May 13 2023 LINKS Andy Huchala, Table of n, a(n) for n = 0..20000 W. R. Parry, A negative result on the representation of modular forms by theta series, J. Reine Angew. Math., 310 (1979), 151-170. EXAMPLE G.f. = 1 + 2*q^4 + 2*q^10 + 2*q^12 + ... PROG (Magma) prec := 90; ls := [[4, 1, 0, -1], [1, 10, 0, 3], [0, 0, 26, 13], [-1, 3, 13, 36]]; S := Matrix(ls); L := LatticeWithGram(S); M := ThetaSeriesModularFormSpace(L); B := Basis(M, prec); T := ThetaSeries(L, 48); coeffs := [Coefficients(T)[2*i-1] : i in [1..23]]; Coefficients(&+[coeffs[i]*B[i] :i in [1..13]]+&+[coeffs[i+1]*B[i] :i in [14..19]] + coeffs[22]*B[20] + coeffs[23]*B[21]); // Andy Huchala, May 13 2023 CROSSREFS Cf. A107498, A107499, A107500, A107501, A107503, A107504, A107505. Sequence in context: A284059 A329767 A356018 * A230419 A146165 A308831 Adjacent sequences: A107499 A107500 A107501 * A107503 A107504 A107505 KEYWORD nonn AUTHOR N. J. A. Sloane, May 28 2005 EXTENSIONS Name clarified and more terms from Andy Huchala, May 13 2023 STATUS approved

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Last modified June 13 09:03 EDT 2024. Contains 373383 sequences. (Running on oeis4.)