Difference between 3^n and the next larger or equal power of 2.

Terms

a(0) =0a(1) =1a(2) =7a(3) =5a(4) =47a(5) =13a(6) =295a(7) =1909a(8) =1631a(9) =13085a(10) =6487a(11) =84997a(12) =517135a(13) =502829a(14) =3605639a(15) =2428309a(16) =24062143a(17) =5077565a(18) =149450423a(19) =985222181a(20) =808182895a(21) =6719515981a(22) =2978678759a(23) =43295774645a(24) =267326277407a(25) =252223018333