# How to solve non_homogenous recurrence in sage using rsolve functions?

a(n+1)^2-5a(n+1)^2+6a(n)^2=7n a0=a1=1
I've used rsolve for this recurrence relation but I got the error min() arg is an empty sequence
any help would be appreciated.```
from sympy import Function, rsolve,Poly
from sympy.abc import n
b=Function('b')
a=Function('a')
f=(b(n+2))^2-5*(b(n+1))^2+6*(b(n))^2-7*n
inits={b(0):1,b(1):1}
b(n)=rsolve(f,b(n),inits)
b(n)
```

the error is:ValueError: min() arg is an empty sequence

Please post the code you are using and the error you are getting.

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@M95, did you mean

`a(n+2)^2 - 5*a(n+1)^2 + 6a(n)^2 = 7*n`

?You wrote

`a(n+1)^2`

twice.@slelievre Yes ,you're right sorry.

Here is the code:

`from sympy import Function, rsolve,Poly from sympy.abc import n b=Function('b') a=Function('a') f=(b(n+2))^2-5*(b(n+1))^2+6*(b(n))^2-7*n inits={b(0):1,b(1):1} b(n)=rsolve(f,b(n),inits) b(n)`