Number of regions in the hyperoctahedral (or cocktail party) graph of order n.

Terms

a(0) =0a(1) =2a(2) =18a(3) =64a(4) =186a(5) =380a(6) =838a(7) =1504a(8) =2242a(9) =4082a(10) =6266a(11) =8320a(12) =13010a(13) =17866a(14) =20218a(15) =31808a(16) =41390a(17) =50100a(18) =66530a(19) =82560a(20) =93446a(21) =123642a(22) =149398a(23) =171920a(24) =212166a(25) =249810a(26) =283678a(27) =340704a(28) =394882a(29) =428892