Sum of integers below 466

Proved

FiniteTriangular.sum_range_466

by carlok · Sep 25, 2026 · Mathlib 0df444a (Lean v4.33.1)

arithmeticfinite-sum

The sum of the nonnegative integers strictly less than $466$ equals $108345$ . Equivalently, $\\sum_{k=0}^{466-1} k = 466(466-1)/2$ .

Preamble

import Mathlib
open Finset

Formal statement

namespace FiniteTriangular

theorem sum_range_466 : ∑ k ∈ range 466, k = 108345 := by sorry

end FiniteTriangular

Source

Elementary arithmetic series: the sum of the first m positive integers is m(m+1)/2, rewritten on Finset.range.