Algebra MM6 4.2.1 (Shining Knight Arms and Armor (hallway)): Arithmetic Series: NWN 0078

In this mini lecture we review what we've learned about arithmetic sequences and note that d is described as the "common difference" and that for the sequence to be arithmetic d must be constant. So 1, 4, 7, 10 ... is an arithmetic sequence but 20, 22, 25, 29 ... is not. So an arithmetic sequence (or arithmetic progression) occurs when the common difference, d, is added to each term in the sequence. The "n" variable in the a sub n = a sub 1 + (n-1)d general arithmetic sequence equation and S sub n = (n/2)(a sub 1 + a sub n) arithmetic series equation is designated the "term number".
Neverwinter Nights:
Zanzi is now in the hallway of the SKA&A and if she were to compare the hallway with the main area, d would be the door as both rooms have a door of similar dimensions and n would be the number of times she would have entered or exited this door.