Sum of integers below 713

Proved

FiniteTriangular.sum_range_713

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

arithmeticfinite-sum

The sum of the nonnegative integers strictly less than $713$ equals $253828$ . Equivalently, $\\sum_{k=0}^{713-1} k = 713(713-1)/2$ .

Preamble

import Mathlib
open Finset

Formal statement

namespace FiniteTriangular

theorem sum_range_713 : ∑ k ∈ range 713, k = 253828 := 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.