a(0)=1, a(1)=6, a(n) = 30*a(n-2) - a(n-1).

Terms

a(0) =1a(1) =6a(2) =24a(3) =156a(4) =564a(5) =4116a(6) =12804a(7) =110676a(8) =273444a(9) =3046836a(10) =5156484a(11) =86248596a(12) =68445924a(13) =2519011956a(14) =-465634236a(15) =76035992916a(16) =-90005019996