Column 4 of triangle A055907.

Terms

a(0) =1a(1) =8a(2) =36a(3) =128a(4) =388a(5) =1050a(6) =2601a(7) =6013a(8) =13141a(9) =27416a(10) =55012a(11) =106816a(12) =201685a(13) =371828a(14) =671630a(15) =1192093a(16) =2084360a(17) =3597991a(18) =6143128a(19) =10391369a(20) =17439285a(21) =29073358a(22) =48199071a(23) =79535657a(24) =130740732a(25) =214230558a(26) =350125952a(27) =571019573a(28) =929690344