Number of polyhexes of class PF2.

Terms

a(0) =4a(1) =28a(2) =176a(3) =950a(4) =4908a(5) =24402a(6) =119240a(7) =575348a(8) =2757460a(9) =13157752a(10) =62638788a(11) =297832008a(12) =1415550920a(13) =6728600060a(14) =31998023632a(15) =152271569872a(16) =725231959452