Triangle of coefficients of polynomials used for g.f.s of columns of A067304.

Terms

a(0) =1a(1) =3a(2) =1a(3) =3a(4) =10a(5) =3a(6) =3a(7) =10a(8) =12a(9) =3a(10) =21a(11) =70a(12) =93a(13) =60a(14) =12a(15) =48a(16) =160a(17) =219a(18) =165a(19) =72a(20) =12a(21) =507a(22) =1690a(23) =2343a(24) =1872a(25) =996a(26) =336a(27) =48a(28) =1461a(29) =4870