var GET=(function(){function f(s){return new g(s);}function g(s){this._s=s.trim().split("\n");this._y=0;}g.prototype.a=function(f){var s=this._s, y=this._y, r;if(typeof s[y]==="string")s[y]=s[y].split(" ").reverse();r=s[y].pop();if(!s[y].length)this._y++;return f?r:+r;};g.prototype.l=function(f){var s=this._s[this._y++].split(" ");return f?s:s.map(a=>+a);};g.prototype.m=function(n,f){var r=this._s.slice(this._y,this._y+=n).map(a=>a.split(" "));return f?r:r.map(a=>a.map(a=>+a));};g.prototype.r=function(n,f){var r=this._s.slice(this._y,this._y+=n);return f?r:r.map(a=>+a);};return f;})();
var o=GET(require("fs").readFileSync("/dev/stdin","utf8"));
function xArray(v){var a=arguments,l=a.length,r="Array(a["+--l+"]).fill(0).map(x=>{return "+v+";})";while(--l)r="Array(a["+l+"]).fill(0).map(x=>"+r+")";return eval(r);}

console.log(main());
function main(){
  var n = o.a();
  var k = o.a();
  var a = Array(n+1);
  var b = Array(n+1);
  var c = Array(n+1);
  a[1] = 0;
  b[1] = 1;
  c[1] = 1;
  while(b[1] < k){
    a[1]++;
    b[1] *= 2;
    c[1] /= 2;
  }
  for(var i = 2; i <= n; i++){
    c[i] = c[i-1];
    b[i] = b[i-1];
    a[i] = a[i-1];
    if(b[i] > 1 && b[i] * i / 2 >= k){
      c[i] *= 2;
      b[i] /= 2;
      a[i]--;
    }
  }
  var ans = 0;
  for(var i = 1; i <= n; i++){
    ans += c[i];
  }
  return ans / n;
}