function triangle(n)
    n == 0 && return []
    n < 0 && throw(DomainError("Invalid n given"))
    rows = [[1]]
    for _ ∈ 2:n
        push!(rows, [a+b for (a,b) ∈ zip([0;rows[end]], [rows[end]; 0])]) 
    end
    rows
end