a(n) = ceiling(1000*log(n)).

Terms

a(0) =0a(1) =694a(2) =1099a(3) =1387a(4) =1610a(5) =1792a(6) =1946a(7) =2080a(8) =2198a(9) =2303a(10) =2398a(11) =2485a(12) =2565a(13) =2640a(14) =2709a(15) =2773a(16) =2834a(17) =2891a(18) =2945a(19) =2996a(20) =3045a(21) =3092a(22) =3136a(23) =3179a(24) =3219a(25) =3259a(26) =3296a(27) =3333a(28) =3368a(29) =3402