qq = [ s + a + b | s <- [0] # qq
	          | a <- [1] # qq
	          | b <- [0] # zs ]
zs : [inf][32]
zs = [0...]

check8 = qq @@ [0 .. 4] == [1, 2, 5, 12, 27]

property prefix = qq @@ [0 .. 4] == [1, 2, 5, 12, 27]