reserve a,b,c,k,m,n for Nat;
reserve i,j,x,y for Integer;
reserve p,q for Prime;
reserve r,s for Real;

theorem Th60:
  i is odd implies i^2 mod 8 = 1
  proof
    assume i is odd;
    then ex j st i = 2*j+1 by ABIAN:1;
    hence thesis by Lm16;
  end;
