kill(all)$

van=facebook.com/LearningCalculus$

f(a,b,i):=a*b+i+(i-1);

7-'f(3,2,1)="7"-f(3,2,1);
23-'f(5,4,2)="23"-f(5,4,2);
47-'f(7,6,3)="47"-f(7,6,3);
79-'f(9,8,4)="79"-f(9,8,4);
99-'f(10,9,5)="99"-f(10,9,5);