reserve X for set;
reserve k,m,n for Nat;
reserve i for Integer;
reserve a,b,c,d,e,g,p,r,x,y for Real;
reserve z for Complex;

theorem
  Basel-seq2.n = (PI^2/6) * (2*n/(2*n+1)) * ((2*n+2)/(2*n+1))
  proof
A1: (p(#)rseq(2,0,2,1)).n = p*rseq(2,0,2,1).n by VALUED_1:6;
    rseq(2,0,2,1).n = (2*n+0)/(2*n+1) & rseq(2,2,2,1).n = (2*n+2)/(2*n+1)
      by Th5;
    hence thesis by A1,VALUED_1:5;
  end;
