Triangle read by rows: The number of chord diagrams on 2n vertices with m marked chords.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =2a(6) =5a(7) =8a(8) =8a(9) =5a(10) =17a(11) =39a(12) =61a(13) =39a(14) =17a(15) =79a(16) =287a(17) =556a(18) =556a(19) =287a(20) =79a(21) =554a(22) =2792a(23) =6910a(24) =9058a(25) =6910a(26) =2792a(27) =554a(28) =5283a(29) =34650