Number of projective meanders.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =8a(5) =12a(6) =52a(7) =86a(8) =400a(9) =710a(10) =3404a(11) =6316a(12) =30888a(13) =59204a(14) =293192a(15) =576018a(16) =2877184a(17) =5764430a(18) =28967428a(19) =58970568a(20) =297634344a(21) =614037754a(22) =3109111064