Lucas(4n)-2, or 5*Fibonacci(2n)^2.

Terms

a(0) =0a(1) =5a(2) =45a(3) =320a(4) =2205a(5) =15125a(6) =103680a(7) =710645a(8) =4870845a(9) =33385280a(10) =228826125a(11) =1568397605a(12) =10749957120a(13) =73681302245a(14) =505019158605