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

Newform orbit 687.2.a.c

Trace form

The 7 newforms in this orbit are conjugate over $\mathbb{Q}$ ; the sum of their $q$ -expansions is

$7q - 2q^{2} - 7q^{3} + 14q^{4} - 6q^{5} + 2q^{6} - 3q^{7} - 18q^{8} + 7q^{9} - 5q^{10} - 10q^{11} - 14q^{12} - 5q^{13} - 10q^{14} + 6q^{15} + 16q^{16} - 17q^{17} - 2q^{18} + 9q^{19} - 20q^{20} + 3q^{21} - 11q^{22} - 14q^{23} + 18q^{24} + O(q^{25})$

Coefficient field

The coefficients $a_n$ generate a number field of degree 7. It is generated by the eigenvalue $\alpha$ of $T = T_{2} + T_{5}$ , whose minimal polynomial is

$x^{7} + 8x^{6} + 9x^{5} - 30x^{4} + 4x^{3} + 16x^{2} - 8x + 1$

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	−7	−6	−3	−10	−5	−17	9	−14	−8	6	2	−11	12	−11	−35	−7	−11	−3	10	−40	13	−17	−7	−40

$\operatorname{tr} a_n$ 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)[2]   # 687.2.a.c

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

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