a(n) = 2*(n+1)*binomial(n+2,4).

Terms

a(0) =6a(1) =40a(2) =150a(3) =420a(4) =980a(5) =2016a(6) =3780a(7) =6600a(8) =10890a(9) =17160a(10) =26026a(11) =38220a(12) =54600a(13) =76160a(14) =104040a(15) =139536a(16) =184110a(17) =239400a(18) =307230a(19) =389620a(20) =488796a(21) =607200a(22) =747500a(23) =912600a(24) =1105650a(25) =1330056a(26) =1589490a(27) =1887900a(28) =2229520a(29) =2618880