should work?

function placeAnGo(moves)
  y = 0
  for y=1,moves,1 do
    turtle.forward(1)
    turtle.placeDown()
  end
end
function pyramid(moves)

  i = 0
  for i=1,4,1 do
     placeAnGo(moves)
     turtle.turnRight()
  end
end



num = read("*n")
o = 0
for o=1,num,1 do
  turtle.forward(1)
  turtle.up(1)
  pyramid(num-o)
end