Number of free orthoplex n-ominoes with cell centers determining n-2 space.

Terms

a(0) =1a(1) =2a(2) =8a(3) =25a(4) =86a(5) =272a(6) =875a(7) =2732a(8) =8505a(9) =26104a(10) =79708a(11) =241522a(12) =728632a(13) =2187951a(14) =6548819a(15) =19542662a(16) =58184124a(17) =172880565a(18) =512837063a(19) =1519158462a(20) =4494920802a(21) =13286473612a(22) =39240530012a(23) =115811180864a(24) =341588823740