Column 6 of triangle A055907.

Terms

a(0) =1a(1) =12a(2) =74a(3) =331a(4) =1212a(5) =3829a(6) =10778a(7) =27651a(8) =65745a(9) =146663a(10) =309831a(11) =624423a(12) =1207701a(13) =2252494a(14) =4067393a(15) =7134576a(16) =12191298a(17) =20342987a(18) =33217622a(19) =53174235a(20) =83580380a(21) =129177701a(22) =196557754a(23) =294776792a(24) =436141322a(25) =637204826a(26) =920020667