The (2^n)-th composite number.

Terms

a(0) =4a(1) =6a(2) =9a(3) =15a(4) =26a(5) =48a(6) =88a(7) =168a(8) =323a(9) =627a(10) =1225a(11) =2406a(12) =4736a(13) =9351a(14) =18504a(15) =36655a(16) =72730a(17) =144450a(18) =287147a(19) =571208a(20) =1136971a(21) =2264215a(22) =4510963a(23) =8990492a(24) =17923944a(25) =35743996a(26) =71298762a(27) =142249762a(28) =283859985a(29) =566537515