原序列：1 221121221221121122121121...
              转换后：0.110010110110010011010010...
              十进制：0.7945071927...
              

i,b,s,x=2,[0,1,1],0,10**1003
while i<9999:b+=[i%2]*(b[i]+1);i+=1;s+=x*b[i]//2**i
print('0.79'+str(s)[1:-3])