Sum of integers below 146

Proved

FiniteTriangular.sum_range_146

by carlok · Sep 24, 2026 · Mathlib 0df444a (Lean v4.33.1)

arithmeticfinite-sum

The sum of the nonnegative integers strictly less than $146$ equals $10585$ . Equivalently, $\sum_{k=0}^{146-1} k = 146(146-1)/2$ .

Preamble

import Mathlib
open Finset

Formal statement

namespace FiniteTriangular

theorem sum_range_146 : ∑ k ∈ range 146, k = 10585 := 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.