English
For hk ≥ 3, the level-1 normalised Eisenstein series E is defined by halving the level-1 Eisenstein series with zero Nebentypus, i.e. E_k = (1/2) eisensteinSeries_MF (mod_cast hk) 0.
Русский
Пусть hk ≥ 3. Нормализованный тождественный ряд Эйзенштейна уровня 1 задан как E_k = (1/2) EisensteinSeries_MF (mod_cast hk) 0.
LaTeX
$$$E_k = \frac{1}{2} \ eisensteinSeries\_MF(\mathrm{mod\_cast}(hk))\ 0 \in \mathcal{M}_{k}(\Gamma(1)).$$$
Lean4
/-- Normalised Eisenstein series of level 1 and weight `k`,
here they have been scaled by `1/2` since we sum over coprime pairs. -/
noncomputable def E {k : ℕ} (hk : 3 ≤ k) : ModularForm Γ(1) k :=
(1 / 2 : ℂ) • eisensteinSeries_MF (mod_cast hk) 0