Partial sums of floor(3^n/7).

Terms

a(0) =0a(1) =0a(2) =1a(3) =4a(4) =15a(5) =49a(6) =153a(7) =465a(8) =1402a(9) =4213a(10) =12648a(11) =37954a(12) =113874a(13) =341634a(14) =1024915a(15) =3074758a(16) =9224289a(17) =27672883a(18) =83018667a(19) =249056019a(20) =747168076a(21) =2241504247a(22) =6724512762a(23) =20173538308a(24) =60520614948a(25) =181561844868