As in 2 / 3 - 3 / 4 4 / 5 - 5 / 6 6 / 7 - 7 / 8, the nth number

As in 2 / 3 - 3 / 4 4 / 5 - 5 / 6 6 / 7 - 7 / 8, the nth number

()n+1/n+2
Symbols in brackets
Judging by the N-1 power of - 1