reserve X for set;
reserve a,b,c,k,m,n for Nat;
reserve i,j for Integer;
reserve r,s for Real;
reserve p,p1,p2,p3 for Prime;
reserve z for Complex;

theorem
  2*(2+1) = 1*(1+1)*(1+2) & 14*(14+1) = 5*(5+1)*(5+2);
