Number of polyhexes of class PF2.

Terms

a(0) =1a(1) =2a(2) =10a(3) =40a(4) =185a(5) =828a(6) =3805a(7) =17411a(8) =80177a(9) =369675a(10) =1710173a(11) =7931011a(12) =36884730a(13) =171987194a(14) =804027444a(15) =3767994408a(16) =17699839325a(17) =83328339997a(18) =393123808821