var      f,g:text;
         v:array[1..1000000] of longint;
         i,ci,sum,n:longint;
begin
assign (f,'fractii.in');reset(f);
assign (g,'fractii.out');rewrite (g);
readln (f,n);
sum:=n*2-1;
fillchar(v,sizeof(v),0);
for i:=2 to n do begin
 ci:=i;
 while ci<=n do begin
  inc(v[ci]);
  ci:=ci+i;
 end;
end;
for i:=1 to n do
 sum:=sum+2*(i-1-v[i]);
writeln (g,sum);
close(f);close(g);
end.