theorem
  6 divides a|^(2*n+1) - a
  proof
    A1: 2 divides  a|^(2*n+1) - a by Th74;
    3 divides a|^(2*n+1) - a by Th75; then
    2*3 divides a|^(2*n+1) - a by INT_2:28,30,PEPIN:41,A1,PEPIN:4;
    hence thesis;
  end;
