a(n) = 3*2^n + 2*3^n.

Terms

a(0) =5a(1) =12a(2) =30a(3) =78a(4) =210a(5) =582a(6) =1650a(7) =4758a(8) =13890a(9) =40902a(10) =121170a(11) =360438a(12) =1075170a(13) =3213222a(14) =9615090a(15) =28796118a(16) =86290050a(17) =258673542a(18) =775627410a(19) =2326095798a(20) =6976714530a(21) =20926997862a(22) =62774702130a(23) =188311523478a(24) =564909404610