Column 3 of triangle in A133721.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =1a(5) =1a(6) =7a(7) =3a(8) =1a(9) =25a(10) =6a(11) =1a(12) =65a(13) =10a(14) =1a(15) =140a(16) =15a(17) =1a(18) =266a(19) =21a(20) =1a(21) =462a(22) =28a(23) =1a(24) =750a(25) =36a(26) =1a(27) =1155a(28) =45a(29) =1