> > (I noticed that the code ran under Racket v5.3.4. but under > Racket v5.2.1. none of the code ran - it showed > for: bad sequence binding clause at: #:break?)
The #:break clause isn't available in the for form of v5.2.1: http://download.racket-lang.org/docs/5.2.1/html/reference/for.html?q=for#(form._((lib._racket/private/base..rkt)._for)) When first learning Racket coming from an imperative programming background it's a good idea to avoid set! for a while to get a feel for the functional aspects of the idiom. Here's a rewrite of the first version of your program with the set!s removed and using straight recursion instead of iteration: #lang racket (define (divides? a b) (= (remainder a b) 0)) (define (L i maxp number) (cond [(= number 1) maxp] [(divides? number i) (L (+ i 2) i (/ number i))] [else (L (+ i 2) maxp number)])) (L 3 0 165) [This also works as #lang scheme] You might want to try a Racket-based text to get immersed in the functional / recursive idiom. HTDP is the usual blanket recommendation (free online), but now there are other options like Realm of Racket. Scheme-based books also have a lot to offer. rosettacode.org has plenty of short Racket and Scheme examples to peruse and compare with examples in familiar languages. Dan
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