a(n) = 100*log_10(n) rounded down.

Terms

a(0) =0a(1) =30a(2) =47a(3) =60a(4) =69a(5) =77a(6) =84a(7) =90a(8) =95a(9) =100a(10) =104a(11) =107a(12) =111a(13) =114a(14) =117a(15) =120a(16) =123a(17) =125a(18) =127a(19) =130a(20) =132a(21) =134a(22) =136a(23) =138a(24) =139a(25) =141a(26) =143a(27) =144a(28) =146a(29) =147