Sum of the nonnegative integers below 1086
ProvedFiniteTriangular.sum_range_1086algebrafinset
The sum of the integers from through equals , which is the triangular number .
Preamble
import Mathlib open Finset
Formal statement
namespace FiniteTriangular theorem sum_range_1086 : ∑ k ∈ range 1086, k = 589155 := by sorry end FiniteTriangular
Source
The closed form for the sum of an initial segment of the nonnegative integers.