a(n) = 11*a(n-2) - 8*a(n-4), starting a(0)=0, a(1)=1, a(2)=5, a(3)=12.

Terms

a(0) =0a(1) =1a(2) =5a(3) =12a(4) =55a(5) =124a(6) =565a(7) =1268a(8) =5775a(9) =12956a(10) =59005a(11) =132372a(12) =602855a(13) =1352444a(14) =6159365a(15) =13817908a(16) =62930175a(17) =141177436a(18) =642957005a(19) =1442408532a(20) =6569085655a(21) =14737074364a(22) =67116286165a(23) =150568549748a(24) =685726462575