#Homework by Mike Murr
#OK to post
#HW5
PermuG := proc(n) local S, i, pi, pi1, L, j, i1, parity; 
option remember; 
if n = 0 then 
  return [[]]; 
end if; 

S := PermuG(n - 1); 

L := []; 

parity := -1; 
for i to nops(S) do 
  pi := S[i]; 
  if parity = 1 then 
    for j to n do 
      pi1 := [op(1 .. j - 1, pi), n, op(j .. nops(pi), pi)]; 
      L := [op(L), pi1]; 
    end do; 
    parity := -parity; 
  else 
    for j from n by -1 to 1 do 
      pi1 := [op(1 .. j - 1, pi), n, op(j .. nops(pi), pi)]; 
      L := [op(L), pi1]; 
    end do; 
    parity := -parity; 
  end if; 
end do; 
L; 
end proc;
> PermuG(2);
> PermuG(1);
> PermuG(2);
> PermuG(3);
> PermuG(4);
> PermuG(5);
> 
;