A107504 Theta series of quadratic form with Gram matrix [ 12, -1, 5, 2; -1, 12, 5, 2; 5, 5, 14, 3; 2, 2, 3, 22].

1, 0, 0, 0, 0, 0, 4, 2, 6, 0, 0, 4, 0, 2, 0, 6, 0, 0, 12, 6, 14, 6, 0, 0, 16, 0, 6, 0, 18, 0, 0, 14, 14, 10, 16, 0, 0, 10, 0, 8, 0, 18, 0, 0, 22, 26, 22, 12, 0, 0, 28, 0, 14, 0, 34, 0, 0, 24, 26, 18, 50, 0, 0, 34, 0, 12, 0, 12, 0, 0, 40, 16, 56, 24, 0, 0, 36

Offset

0,7

Comments

G.f. is theta_8 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 14 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 + 4*q^12 + 2*q^14 + 6*q^16 + ...

Prog

(Magma)
prec := 90;
ls := [[12, -1, 5, 2], [-1, 12, 5, 2], [5, 5, 14, 3], [2, 2, 3, 22]];
S := Matrix(ls);
L := LatticeWithGram(S);
M := ThetaSeriesModularFormSpace(L);
B := Basis(M, prec);
T<q> := 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 14 2023

Crossrefs

Cf. A107498-A107503, A107505.

Sequence in context: A283747 A180109 A019170 * A141674 A329323 A178394

Adjacent sequences: A107501 A107502 A107503 * A107505 A107506 A107507

Keyword

nonn

Author

N. J. A. Sloane, May 28 2005

Extensions

Name clarified and more terms from Andy Huchala, May 14 2023

Status

approved