Number of 4-cycles in the n X n black bishop graph.

Terms

a(0) =0a(1) =0a(2) =0a(3) =6a(4) =39a(5) =106a(6) =321a(7) =644a(8) =1402a(9) =2412a(10) =4382a(11) =6842a(12) =11097a(13) =16198a(14) =24311a(15) =33768a(16) =47908a(17) =64056a(18) =87084a(19) =112974a(20) =148539a(21) =188034a(22) =240669a(23) =298540a(24) =373758a(25) =455780a(26) =560170a(27) =673218a(28) =814541a(29) =966686