with(ArrayTools):

spiralArray := proc(size::integer)
 local M, sideLength, count, i, j:
 M := Matrix(size):
 count := 0:
 sideLength := size:
 for i from 1 to ceil(sideLength / 2) do
  for j from 1 to sideLength do
   M[i,i + j - 1] := count++:
  end:
  for j from 1 to sideLength - 1 do
   M[i + j, sideLength + i - 1] := count++:
  end:
  for j from 1 to sideLength - 1 do
   M[i + sideLength - 1, sideLength - j + i - 1] := count++:
  end:
  for j from 1 to sideLength - 2 do
   M[sideLength + i - j - 1, i] := count++
  end:
  sideLength -= 2:
 end:
 return M;
end proc:

spiralArray(5);