Triangle of rooted planar maps up to orientation-preserving isomorphisms.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =1a(7) =2a(8) =3a(9) =4a(10) =1a(11) =2a(12) =8a(13) =12a(14) =14a(15) =1a(16) =3a(17) =12a(18) =30a(19) =43a(20) =49a(21) =1a(22) =3a(23) =22a(24) =63a(25) =134a(26) =189a(27) =216a(28) =1a(29) =4