Sum of tail length of S over all 2^n strings S consisting of n 2's and 3's.

Terms

a(0) =0a(1) =3a(2) =6a(3) =18a(4) =39a(5) =96a(6) =201a(7) =582a(8) =1220a(9) =2590a(10) =5345a(11) =10919a(12) =21859a(13) =44167a(14) =88629a(15) =178050a(16) =356598a(17) =715084a(18) =1431514a(19) =2866876a(20) =5736311a(21) =11480839a(22) =22966942a(23) =45949687a(24) =91910241a(25) =183852468a(26) =367726473a(27) =735517466a(28) =1471078571a(29) =2942286009