Sum of integers below 177

Proved

FiniteTriangular.sum_range_177

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

arithmeticfinite-sum

The sum of the nonnegative integers strictly less than $177$ equals $15576$ . Equivalently, $\sum_{k=0}^{177-1} k = 177(177-1)/2$ .

Preamble

import Mathlib
open Finset

Formal statement

namespace FiniteTriangular

theorem sum_range_177 : ∑ k ∈ range 177, k = 15576 := 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.