Question

What is the closed linear form for sequence a1=13 and an+1=an+4

Answer 1

`a_(n+1)=a_n+4`

`a_(n+1)=(a_(n-1)+4)+4=a_(n-1)+2*4`

`a_(n+1)=(a_(n-2)+4)+2*4=a_(n-2)+3*4`

and so on, until you're left with


`a_(n+1)=a_1+4n=4n+13`