
theorem Rascal 6 = <*1,6,9,10,9,6,1*>
  proof
    reconsider f = Rascal 6 as (6+1)-element FinSequence;
    dom f = Seg (6 + 1) by Def1; then
    1 in dom f & 2 in dom f & 3 in dom f & 4 in dom f &
      5 in dom f & 6 in dom f & 7 in dom f; then
    f.1 = (1-1)*(6+1-1) + 1 &
    f.2 = (2-1)*(6+1-2) + 1 &
    f.3 = (3-1)*(6+1-3) + 1 &
    f.4 = (4-1)*(6+1-4) + 1 &
    f.5 = (5-1)*(6+1-5) + 1 &
    f.6 = (6-1)*(6+1-6) + 1 &
    f.7 = (7-1)*(6+1-7) + 1 by Def1;
    hence thesis;
  end;
