Atlas › Modular forms › Weight 2 › Level 687 › 687.2.a › 687.2.a.b

Newform orbit 687.2.a.b

Trace form

The 5 newforms in this orbit are conjugate over $\mathbb{Q}$ ; the sum of their $q$ -expansions is

$5q - 2q^{2} + 5q^{3} - 3q^{5} - 2q^{6} - 10q^{7} - 6q^{8} + 5q^{9} - 6q^{10} - 2q^{11} - 13q^{13} + 7q^{14} - 3q^{15} + 2q^{16} - 14q^{17} - 2q^{18} - 17q^{19} + 5q^{20} - 10q^{21} - 5q^{22} + 3q^{23} - 6q^{24} + O(q^{25})$

Coefficient field

The coefficients $a_n$ generate a number field of degree 5. It is generated by the eigenvalue $\alpha$ of $T = T_{2} + T_{5}$ , whose minimal polynomial is

$x^{5} + 5x^{4} + 5x^{3} - 6x^{2} - 7x + 1$

Atkin–Lehner signs

$p$	$w_p$
3	$-1$
229	$-1$

For $p \parallel N$ every form in the orbit has $a_p = -p^{k/2-1} w_p$ . The Fricke sign is $w_N = +1$ , so the sign of the functional equation is $(-1)^{k/2} w_N = -1$ : each L-function in the orbit has odd analytic rank.

Traces of Hecke eigenvalues

$p$	2	3	5	7	11	13	17	19	23	29	31	37	41	43	47	53	59	61	67	71	73	79	83	89	97
$\operatorname{tr} a_p$	−2	5	−3	−10	−2	−13	−14	−17	3	2	−11	−7	−19	−14	4	6	14	2	−16	16	−34	−10	1	−5	−19

$\operatorname{tr} a_n$ for every $n \le 1000$ is in the JSON.

Provenance

Stored in the atlas: computed by Sagebrush's modular symbols engine in 0.225 s (one thread) and proven: the dimensions are certified, and the characteristic polynomial of $T$ over $\mathbb{Z}$ is reconstructed by CRT past a rigorous coefficient bound. The label, dimension and $\operatorname{tr} a_p$ for every $p < 1000$ equal LMFDB's.

The engine's checks

dim M^+ at levels [1, 3, 229, 687]: [0, 1, 19, 78] (certified at ell = 2147478649)
T = [(2, 1), (5, 1)]; h of degree 39 = 1 x 39 (phi(ord eps) x dim S_k^new); 4 primes, 0 rejected

Open in the notebook · JSON · stored data

Recompute it yourself

In Sage mode at sagebrush.space (or npx sagebrush --sage):

newform_orbits(687, 2)[1]   # 687.2.a.b

With the Rust engine (source), in engine/:

cargo run --release -p sagebrush-web --example atlas -- 687:2 1000