> (first-perfect-after 0)
6
> (first-perfect-after 6)
28
> (first-perfect-after 28)
496
> (first-perfect-after 496)
8128 ;; takes 1.5 seconds on i7 1.9 GHz 8-core processor
> (first-perfect-after 8128)
;; quit after 10 minutes
It is currently an open question whether there are any odd perfect numbers.