Newforms
Hecke characteristic polynomials
The eigenvalue of T=T11โ+3T13โ+5T17โ+7T19โ+9T23โ+11T29โ generates each orbit's coefficient field; on the newspace its characteristic polynomial factors over Q as one irreducible factor per orbit:
Dimensions
| Newforms S2newโ(ฮ0โ(420)) | 4 |
|---|
| Old forms | 81 |
| Cusp forms S2โ(ฮ0โ(420)) | 85 |
|---|
| Eisenstein series E2โ(ฮ0โ(420)) | 23 |
| Modular forms M2โ(ฮ0โ(420)) | 108 |
|---|
Decomposition of the old subspace
S2oldโ(ฮ0โ(420))= S2newโ(ฮ0โ(14))โ8 โ S2newโ(ฮ0โ(15))โ6 โ S2newโ(ฮ0โ(20))โ4 โ S2newโ(ฮ0โ(21))โ6 โ S2newโ(ฮ0โ(30))โ4 โ S2newโ(ฮ0โ(35))โ6 โ S2newโ(ฮ0โ(42))โ4 โ S2newโ(ฮ0โ(70))โ4 โ S2newโ(ฮ0โ(84))โ2 โ S2newโ(ฮ0โ(105))โ3 โ S2newโ(ฮ0โ(140))โ2 โ S2newโ(ฮ0โ(210))โ2
Provenance
Stored in the atlas: computed by Sagebrush's modular symbols engine in 0.303 s (one thread) and proven: the dimensions are certified, and the characteristic polynomial of T over Z is reconstructed by CRT past a rigorous coefficient bound.
The engine's checks
dim M^+ at levels [1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210, 420]: [0, 1, 1, 2, 1, 3, 1, 3, 5, 4, 4, 6, 4, 7, 10, 6, 12, 18, 16, 22, 20, 30, 56, 108] (certified at ell = 2147483629)T = [(11, 1), (13, 3), (17, 5), (19, 7), (23, 9), (29, 11)]; h of degree 4 = 1 x 4 (phi(ord eps) x dim S_k^new); 2 primes, 0 rejected
Recompute it yourself
In Sage mode at sagebrush.space (or npx sagebrush --sage):
newform_orbits(420, 2)
With the Rust engine (source), in engine/:
cargo run --release -p sagebrush-web --example atlas -- 420:2 1000
โ 419.2.a ยท 421.2.a โ