Powers of cube root of 4 rounded up.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =7a(5) =11a(6) =16a(7) =26a(8) =41a(9) =64a(10) =102a(11) =162a(12) =256a(13) =407a(14) =646a(15) =1024a(16) =1626a(17) =2581a(18) =4096a(19) =6502a(20) =10322a(21) =16384a(22) =26008a(23) =41286a(24) =65536a(25) =104032a(26) =165141a(27) =262144a(28) =416128a(29) =660562