Minetest

O = 46
L = O

function mFor(x)
  while x~=0 do
    turtle.dig()
    turtle.forward()
    x = x - 1
  end
end

function aTurn(x)
  mFor(x)
  turtle.turnLeft()
  mFor(x)
  turtle.turnLeft()
  mFor(x)
  turtle.turnLeft()
  mFor(x-1)
  turtle.turnLeft()
end

while L-y~=y do
  aTurn(L-y)
  y = y + 1
end