The number of labeled biconnected squaregraphs with n vertices.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =0a(5) =3a(6) =0a(7) =12a(8) =2a(9) =55a(10) =22a(11) =278a(12) =182a(13) =1506a(14) =1378a(15) =8595a(16) =10040a(17) =51134a(18) =71814a(19) =314693a(20) =509200