Shifts left when MASKCONVolved with itself.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =12a(5) =24a(6) =72a(7) =192a(8) =720a(9) =1440a(10) =4320a(11) =11520a(12) =43200a(13) =103680a(14) =362880a(15) =1105920a(16) =4665600a(17) =9331200a(18) =27993600a(19) =74649600a(20) =279936000a(21) =671846400a(22) =2351462400a(23) =7166361600a(24) =30233088000a(25) =67184640000a(26) =221709312000a(27) =644972544000