thats the arithmetic sequence formula!
an = the term u want to find
a1= first term in the list of ordered #s
n= the term position
d= common difference of any pair of consecutive and adjacent #s
a^n=a^1+(n-1)+d is a formula to help find a term in a sequence.
EX: find the 35th term in thr arithmetuc sequence 3,9,15,21....
3 THINGS NEEDED:
1. the first term (a1)
2. common difference (d)
3. term position (n)
the first term = a1 = 3
difference = d = 6
term position = n = 35
an = a1 + (n-1)d
a35 = 3 + (35-1)6
= 3 + (34)6
= 3 + 204
a35 = 207