Answer:
a(n)= 4*n+1
a(n+1)=5+4*n
Explanation:
The sequence 5, 9, 13, 17 is the ariphmetic progression where a(1)=5 is the first member of the progression and the diference is d=9-5=4 (the distance between the neighboring members)
For ariphmetic progression is known that n- term is equal to
a(n)=a(1)+d*(n-1)
So for our case
a(n)=5+4(n-1)=5+4n-4=4n+1
a(n+1)= 5+4(n+1-1)= 5+4n