; the seven immortals
(define (immortals n)
(define (binom n k)
(let loop ((n n) (k k) (b 1))
(if (zero? k) b
(loop (- n 1) (- k 1)
(* (/ b k) n)))))
(define (fact2 n)
(if (< n 1) 1
(* n (fact2 (- n 2)))))
(let loop ((k n) (i 0))
(if (zero? k) i
(loop (- k 1)
(+ i (* (binom n k)
(fact2 (+ k k -3))))))))
(do ((n 1 (+ n 1))) (#f)
(display n) (display #\tab)
(display (immortals n))
(newline))