Atlas › Modular forms › Weight 2 › Level 876 › 876.2.a › 876.2.a.b

Newform orbit 876.2.a.b

$q$ -expansion

$q + q^{3} - q^{5} - 2q^{7} + q^{9} - 4q^{11} - 2q^{13} - q^{15} + q^{17} - 7q^{19} - 2q^{21} + O(q^{25})$

Coefficient field

The coefficients $a_n$ generate $\mathbb{Q}$ . The eigenvalue of $T = T_{5} + 3T_{7}$ is a root of

$x + 7$

Atkin–Lehner signs

$p$	$w_p$
2	— ( $2^2 \mid 876$ )
3	$-1$
73	$+1$

For $p \parallel N$ every form in the orbit has $a_p = -p^{k/2-1} w_p$ .

Elliptic curve

By modularity this newform is the one attached to the isogeny class 876.b (Cremona's 876b). Its optimal curve 876b1 is

$y^2 = x^3 + x^2 - 61x + 191$

of rank 1 with torsion of order 1. Its $a_p$ , computed by Sagebrush's point-counting engine, equal the newform's for every prime $p < 1000$ .

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
$\operatorname{tr} a_p$	0	1	−1	−2	−4	−2	1	−7	0	6	−2	−3	−6	2	−7	3	11	7	−3	−2	−1	−3	−9	6	−19

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

Sato–Tate

The normalized $a_p / 2p^{1/2}$ for the primes $p < 1000$ not dividing 876, against the semicircle $\tfrac{2}{\pi}\sqrt{1 - x^2}$ :

Provenance

Stored in the atlas: computed by Sagebrush's modular symbols engine in 0.324 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, 2, 3, 4, 6, 12, 73, 146, 219, 292, 438, 876]: [0, 1, 1, 2, 3, 5, 6, 20, 26, 40, 78, 154] (certified at ell = 2147482873)
T = [(5, 1), (7, 3)]; h of degree 12 = 1 x 12 (phi(ord eps) x dim S_k^new); 2 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(876, 2)[1]   # 876.2.a.b

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

cargo run --release -p sagebrush-web --example atlas -- 876:2 1000