6(7+1)(7²+1)([7^4]1)([7^8]+1)+1 =(7-1)(7+1)(7²+1)([7^4]1)([7^8]+1)+1 =(7²-1)(7²+1)([7^4]+1)([7^8]+1)+1 =(7^4-1)([7^4]+1)([7^8]+1)+1 =(7^8-1)(7^8+1)+1 =7^16-1+1=7^16