a(n) = (n+1)(n+2)^2*(n+3)^2*(n+4)(5n^2 + 21n + 20)/2880.

Terms

a(0) =1a(1) =23a(2) =205a(3) =1120a(4) =4508a(5) =14700a(6) =41076a(7) =101970a(8) =230505a(9) =482911a(10) =949949a(11) =1772134a(12) =3159520a(13) =5416880a(14) =8975184a(15) =14430348a(16) =22590297a(17) =34531455a(18) =51665845a(19) =75820052a(20) =109327372a(21) =155134540a(22) =216924500a(23) =299256750a(24) =407726865a(25) =549146871a(26) =731748213