Number of squarefree bipartite graphs on n vertices.

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =10a(5) =21a(6) =39a(7) =86a(8) =182a(9) =440a(10) =1074a(11) =2941a(12) =8424a(13) =26720a(14) =90883a(15) =340253a(16) =1384567a(17) =6186907a(18) =30219769a(19) =161763233a(20) =946742190a(21) =6054606722a(22) =42229136988a(23) =320741332093