theorem
  primesFinS 2 = <*2,3*>
  proof
    set f = primesFinS 2;
A1: len f = 2 by Def1;
    f.(0+1) = 2 & f.(1+1) = 3 by Def1,MOEBIUS2:8,10;
    hence thesis by A1,FINSEQ_1:44;
  end;
