Column 3 of triangle A055898.

Terms

a(0) =1a(1) =7a(2) =31a(3) =101a(4) =272a(5) =636a(6) =1340a(7) =2600a(8) =4725a(9) =8135a(10) =13391a(11) =21217a(12) =32536a(13) =48496a(14) =70512a(15) =100296a(16) =139905a(17) =191775a(18) =258775a(19) =344245a(20) =452056a(21) =586652a(22) =753116a(23) =957216a(24) =1205477a(25) =1505231a(26) =1864695a(27) =2293025a(28) =2800400a(29) =3398080