1*7^2-8
1*7^4-8
1*7^8-8
1*7^10-8
1*7^2-6
1*7^3-6
1*7^6-6
1*7^9-6
1*7^1+6
1*7^3+6
6*7^1-1
6*7^2-1
6*7^7-1
6*7^1+1
6*7^4+1
6*7^9+1
8*7^4-1
8*7^7-1