procedure main()

write("Non-cube Squares (21st to 30th):")
every (k := 0, s := noncubesquares()) do
   if(k +:= 1) > 30 then break
   else write(20 < k," : ",s)
end

procedure mthpower(m)   #: generate i^m for i = 0,1,...
while (/i := 0) | (i +:= 1) do suspend i^m
end

procedure noncubesquares()  #: filter for squares that aren't cubes
cu := create mthpower(3)    # co-expressions so that we can
sq := create mthpower(2)    # ... get our results where we need

repeat {
   if c === s then  ( c := @cu , s := @sq )
   else if s > c then c := @cu
   else {
      suspend s
      s := @sq
      }
   }
end