Number of loopless tree-rooted planar maps with 3 vertices and n faces and no isthmuses.

Terms

a(0) =0a(1) =3a(2) =36a(3) =135a(4) =360a(5) =798a(6) =1568a(7) =2826a(8) =4770a(9) =7645a(10) =11748a(11) =17433a(12) =25116a(13) =35280a(14) =48480a(15) =65348a(16) =86598a(17) =113031a(18) =145540a(19) =185115a(20) =232848a(21) =289938a(22) =357696a(23) =437550a(24) =531050a(25) =639873a(26) =765828a(27) =910861a(28) =1077060a(29) =1266660