a(n) = 3*a(n-1) - 2*a(n-2) with a(0)=24 and a(1)=60.

Terms

a(0) =24a(1) =60a(2) =132a(3) =276a(4) =564a(5) =1140a(6) =2292a(7) =4596a(8) =9204a(9) =18420a(10) =36852a(11) =73716a(12) =147444a(13) =294900a(14) =589812a(15) =1179636a(16) =2359284a(17) =4718580a(18) =9437172a(19) =18874356a(20) =37748724a(21) =75497460a(22) =150994932a(23) =301989876a(24) =603979764a(25) =1207959540a(26) =2415919092a(27) =4831838196a(28) =9663676404a(29) =19327352820