from __future__ import generators

def bifac(k):
    n=k+k+1L
    x=[]
    o=[]
    r=binom(n)
    for i in r:
        x.append(i)
    del x[n]
    while n>0L:
        n=n-1
        f=x[n]
        o=o+[f]
        i=n//2L
        r=0L
        for j in binom(i):
            x[i+r]-=f*j
            r+=1
        n-=1L
    return o
       

def binom(n):
    nz=n*1L
    nn=1L
    p = 1L
    yield(p)
    while nn<=n:
        p=(p*nz)//nn
        nz-=1L
        nn+=1L
        yield(p)
    return

def ggT(a,b):
    a=abs(a)
    b=abs(b)
    if b<a:
        h=a
        a=b
        b=h
    while a>0:
        h=b
        b=a
        a=h%a
    return b

def pinom(n):
    k=1L
    vz=[3L]
    vn=[1L]
    az=9L
    an=1L
    while k<=n:
        s=2*k+1L
        v2=bifac(k)
        fz=vz[0]
        fn=vn[0]*s
        g=ggT(fz,fn)
        fz=fz//g
        fn=fn//g
        az=az*fn+an*fz
        an=an*fn
        g=ggT(an,az)
        an=an//g
        az=az//g
        i=1
        oz=[]
        on=[]
        while i<len(v2):
            hz=-v2[i]*fz
            hn=fn
            if i<len(vz):
                hz=hz*vn[i]+hn*vz[i]
                hn=hn*vn[i]
            g=ggT(hz,hn)
            oz.append(hz//g)
            on.append(hn//g)
            i+=1
        vz=oz
        vn=on
        k+=1L
    return az,an,vz,vn

def pivalue(i,j):
    val=pinom(i)
    r=(val[0]*1.0)/val[1]
    for i1 in range(i):
        f=(val[2][i1]*1.0)/val[3][i1]
        for n in range(1,j+1):
            r=r+f*((1.0/n/(n+1.0))**(i1+i+2.0))
    return r
    

print pivalue(2,2)