a(n) is the sum of (3^n mod 2^k) for k such that 2^k < 3^n.

Terms

a(0) =1a(1) =3a(2) =18a(3) =38a(4) =195a(5) =585a(6) =607a(7) =3948a(8) =11976a(9) =42415a(10) =127921a(11) =56067a(12) =666938a(13) =2082798a(14) =10769251a(15) =22610393a(16) =110616780a(17) =315726436a(18) =408228944a(19) =2384863439a(20) =7159829169a(21) =23350950650a(22) =74348867826a(23) =49863537606a(24) =401947783347