Incorrect duplicate of A004146.

Terms

a(0) =1a(1) =5a(2) =8a(3) =45a(4) =121a(5) =320a(6) =841a(7) =2205a(8) =5776a(9) =15125a(10) =39601a(11) =103680a(12) =271441a(13) =710645a(14) =1860496a(15) =4870845a(16) =12752041a(17) =33385280a(18) =87403801a(19) =228826125a(20) =599074576a(21) =1568397605a(22) =4106118241a(23) =10749957120a(24) =28143753121a(25) =73681302245a(26) =192900153616a(27) =505019158605