Triangular array of numbers of 2-polymatroids of rank k on n labeled points, for n>=0, 0<=k<=2n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =3a(6) =6a(7) =3a(8) =1a(9) =1a(10) =7a(11) =29a(12) =41a(13) =29a(14) =7a(15) =1a(16) =1a(17) =15a(18) =135a(19) =477a(20) =784a(21) =477a(22) =135a(23) =15a(24) =1a(25) =1a(26) =31a(27) =642a(28) =5957a(29) =27375