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

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =4a(7) =2a(8) =1a(9) =1a(10) =3a(11) =10a(12) =12a(13) =10a(14) =3a(15) =1a(16) =1a(17) =4a(18) =21a(19) =49a(20) =78a(21) =49a(22) =21a(23) =4a(24) =1a(25) =1a(26) =5a(27) =39a(28) =172a(29) =584