a(n) = floor[geometric mean of first n factorials].

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =17a(6) =38a(7) =91a(8) =230a(9) =605a(10) =1661a(11) =4735a(12) =13998a(13) =42795a(14) =135021a(15) =438826a(16) =1466690a(17) =5033778a(18) =17716515a(19) =63865399a(20) =235547709a(21) =887938469a(22) =3418054843a(23) =13424588130a(24) =53753996494a(25) =219278318407a(26) =910679550679