1*2^15+1*2^14+1*2^13+1*2^12+1*2^11+1*2^10+1*2^9+1*2^8+1*2^7+1*2^6+1*2^5+1*2^4+1*2^3+1*2^2+1*2^1+1*2^0=65535
2^16 -1
