a(n) = ceiling(log(n)*2^n/n).

Terms

a(0) =0a(1) =2a(2) =3a(3) =6a(4) =11a(5) =20a(6) =36a(7) =67a(8) =125a(9) =236a(10) =447a(11) =849a(12) =1617a(13) =3089a(14) =5916a(15) =11357a(16) =21845a(17) =42095a(18) =81250a(19) =157063a(20) =304040a(21) =589308a(22) =1143584a(23) =2221621a(24) =4320302a(25) =8409507a(26) =16383694a(27) =31945780a(28) =62338041a(29) =121733597