a(n) = 1000*log_10(n) rounded down.

Terms

a(0) =0a(1) =301a(2) =477a(3) =602a(4) =698a(5) =778a(6) =845a(7) =903a(8) =954a(9) =1000a(10) =1041a(11) =1079a(12) =1113a(13) =1146a(14) =1176a(15) =1204a(16) =1230a(17) =1255a(18) =1278a(19) =1301a(20) =1322a(21) =1342a(22) =1361a(23) =1380a(24) =1397a(25) =1414a(26) =1431a(27) =1447a(28) =1462a(29) =1477