English
The nth coefficient of the ordinary hypergeometric series is given by (n!^{-1}) · (ascPochhammer n).eval(a) · (ascPochhammer n).eval(b) · ((ascPochhammer n).eval(c))^{-1}.
Русский
n-й коэффициент обыкновенного гипергеометрического ряда равен (n!^{-1}) · (ascPochhammer n).eval(a) · (ascPochhammer n).eval(b) · ((ascPochhammer n).eval(c))^{-1}.
LaTeX
$$$\\displaystyle \\text{coeff}(n) = (n!^{-1}) \\cdot (\\mathrm{ascPochhammer}\\;\\mathbb{K}\\;n).\\mathrm{eval}(a) \\cdot (\\mathrm{ascPochhammer}\\;\\mathbb{K}\\;n).\\mathrm{eval}(b) \\cdot (\\mathrm{ascPochhammer}\\;\\mathbb{K}\\;n).\\mathrm{eval}(c)^{-1}$$$
Lean4
/-- The coefficients in the ordinary hypergeometric sum. -/
noncomputable abbrev ordinaryHypergeometricCoefficient (a b c : 𝕂) (n : ℕ) :=
((n !⁻¹ : 𝕂) * (ascPochhammer 𝕂 n).eval a * (ascPochhammer 𝕂 n).eval b * ((ascPochhammer 𝕂 n).eval c)⁻¹)