:: [recur-quot] ( vals quot -- quot' )
    [
        vals first2 quot call
        vals second vals set-first vals set-second
    ] ;

! quot should be ( a[n-1] a[n] -- a[n+1] )
:: 2-recurrence ( n start-vals quot -- end-vals )
    start-vals clone dup quot [recur-quot] [ n ] dip
    [ over 0 > ]
    [ [ 1 - ] [ dup call( -- ) ] bi* ] while 2drop ;