Number of regions in a regular drawing of the complete bipartite graph K_{n,n}.

Terms

a(0) =0a(1) =2a(2) =12a(3) =40a(4) =96a(5) =204a(6) =368a(7) =634a(8) =1012a(9) =1544a(10) =2236a(11) =3186a(12) =4360a(13) =5898a(14) =7764a(15) =10022a(16) =12712a(17) =16026a(18) =19844a(19) =24448a(20) =29708a(21) =35756a(22) =42604a(23) =50602a(24) =59496a(25) =69650a(26) =80940a(27) =93600a(28) =107540a(29) =123316