Tak in nim

Tak.nim

var 
  i:int = 0 

proc tak(x, y, z:int):int =
  if x <= y:
    y
  else:
    i = i + 1
    tak(tak(x-1, y, z),tak(y-1, z, x),tak(z-1, x, y))

proc takeuchi_number(n:int):int = 
  i = 0
  discard tak(n,0,n+1)
  i

when isMainModule:
  echo(takeuchi_number(14))