The equation for finding the equation of an arithmetic sequence is an=a1+(n-1)d, where n is the input for the sequence, a1 is the first term, and d is the difference between each term.
a1= 1/4
d= 1/4
an= 1/4 + (n-1)(1/2) - First you need to distribute the 1/2 to both the n and -1 to get: an= 1/4 + 1/2n -1/2.
Then you need to add like terms (1/4-1/2) to get an=1/2n-1/4. Hope this helps!