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

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =10a(5) =19a(6) =36a(7) =67a(8) =125a(9) =236a(10) =446a(11) =848a(12) =1616a(13) =3088a(14) =5916a(15) =11357a(16) =21844a(17) =42094a(18) =81249a(19) =157063a(20) =304039a(21) =589308a(22) =1143584a(23) =2221621a(24) =4320302a(25) =8409506a(26) =16383694a(27) =31945780a(28) =62338041a(29) =121733596