Powers of cube root of 16 rounded up.

Terms

a(0) =1a(1) =3a(2) =7a(3) =16a(4) =41a(5) =102a(6) =256a(7) =646a(8) =1626a(9) =4096a(10) =10322a(11) =26008a(12) =65536a(13) =165141a(14) =416128a(15) =1048576a(16) =2642246a(17) =6658043a(18) =16777216a(19) =42275936a(20) =106528682a(21) =268435456a(22) =676414964a(23) =1704458901a(24) =4294967296a(25) =10822639410a(26) =27271342416a(27) =68719476736a(28) =173162230555