a(n) = floor((4*Pi)^n * n!).A163585a(n) = floor((4*Pi)^n * n!).Terms a(0) =1a(1) =12a(2) =315a(3) =11906a(4) =598481a(5) =37603698a(6) =2835252098a(7) =249401800589External referencesoeis: A163585