DouKaku?

#!/usr/bin/env gosh

(define *max* 100000000)

(define (func n b)
  (let ((quo (quotient n 10)))
    (if (zero? quo) (modulo n 10)
        (+ (* (func quo b) b) (func (modulo n 10) b)))))

(define (foo x)
  (cond ((zero? (modulo (func x 13) x)) x)
        ((> x *max*) 'over)
        (else (foo (+ x 1)))))

(print (foo 10))