Number of 2-sided n-polycairos.

Terms

a(0) =1a(1) =2a(2) =5a(3) =17a(4) =55a(5) =206a(6) =781a(7) =3099a(8) =12421a(9) =50725a(10) =208870a(11) =868238a(12) =3631673a(13) =15281827a(14) =64610493a(15) =274346429a(16) =1169219224a(17) =4999544053a(18) =21440702381a(19) =92192889106