include builtins/mpfr.e
function is_perfect(integer num)
mpq tot = mpq_init(),
    fth = mpq_init()
sequence f = factors(num,1)
    for i=1 to length(f) do
        mpq_set_si(fth,1,f[i])
        mpq_add(tot,tot,fth)
    end for
    return mpq_cmp_si(tot,2,1)=0
end function

procedure get_perfect_numbers()
atom t0 = time()
    for i=2 to power(2,19) do
        if is_perfect(i) then
            printf(1,"perfect: %d\n",i)
        end if
    end for
    printf(1,"elapsed: %3.2f seconds\n",time()-t0)

    integer pn5 = power(2,12)*(power(2,13)-1) -- 5th perfect number
    if is_perfect(pn5) then
        printf(1,"perfect: %d\n",pn5)
    end if
end procedure

get_perfect_numbers()