(define colors '("white" "black" "red" "blue" "pink" "orange" "maroon" "red" "blue" "yellow" "green" "silver" "teal" "tan" "gold" "olive" "turquoise" "navy" "indigo" "hotpink" "maroon"))

(define (row xloc xstart xend xinc ystart yend yinc radius maxiterations)
	(if (>= xloc xend) nil
		(begin
			(column xloc ystart ystart yend yinc radius maxiterations)
			(row (+ xloc xinc) xstart xend xinc ystart yend yinc radius maxiterations)
			)))

(define (column xloc yloc ystart yend yinc radius maxiterations)
	(if (>= yloc yend) nil
		(begin
			(sequence xloc yloc 0 0 radius 0 maxiterations colors)
			(column xloc (+ yloc yinc) ystart yend yinc radius maxiterations)
			)))

(define (sequence xloc yloc z_xloc z_yloc radius iteration maxiterations colorsel)
	(if (or (> (+ (* z_xloc z_xloc) (* z_yloc z_yloc)) (* radius radius)) (> iteration maxiterations))
		(if (> iteration 4)
			(begin
				(penup)
				(goto (floor (* yloc 100)) (floor (* xloc 100)))
				(pendown)
				(begin_fill)
				(if (and (and (> yloc -0.05) (< yloc 0.05)) (< xloc -1.25)) (color "brown") (color (car colorsel)))
				(circle (floor (* iteration 0.5)))
				(end_fill)
				))
		(sequence xloc yloc (+ (- (* z_xloc z_xloc) (* z_yloc z_yloc)) xloc) (+ (+ (* z_xloc z_yloc) (* z_xloc z_yloc)) yloc) radius (+ iteration 1) maxiterations (cdr colorsel))))

; Recursion program
(define (picture)
	(begin
		(clear)
		(color "blue")
		(speed 0)
		(penup)
		(goto -400 -400)
		(pendown)
		(begin_fill)
		(goto 400 -400)
		(goto 400 400)
		(goto -400 400)
		(goto -400 -400)
		(end_fill)
		(penup)
		(color "green")
		(goto -400 -400)
		(pendown)
		(begin_fill)
		(goto 400 -400)
		(goto 400 -200)
		(goto -400 -200)
		(goto -400 -400)
		(end_fill)
		(row -2 -2 2 0.1 -2 2 0.1 2 9)
		(penup)
		(goto 250 300)
		(color "gold")
		(pendown)
		(begin_fill)
		(circle 75)
		(end_fill)
		(hideturtle)))