a(n) = floor(Pi^n/Zeta(n)).

Terms

a(0) =0a(1) =6a(2) =25a(3) =90a(4) =295a(5) =945a(6) =2995a(7) =9450a(8) =29749a(9) =93555a(10) =294058a(11) =924041a(12) =2903320a(13) =9121612a(14) =28657269a(15) =90030844a(16) =282842403a(17) =888579011a(18) =2791558622a(19) =8769948429a(20) =27551618702a(21) =86555983552a(22) =271923674474a(23) =854273468992