n Sum_n Sum_n Sum_n.

Terms

a(0) =1a(1) =30a(2) =270a(3) =1400a(4) =5250a(5) =15876a(6) =41160a(7) =95040a(8) =200475a(9) =393250a(10) =726726a(11) =1277640a(12) =2153060a(13) =3498600a(14) =5508000a(15) =8434176a(16) =12601845a(17) =18421830a(18) =26407150a(19) =37191000a(20) =51546726a(21) =70409900a(22) =94902600a(23) =126360000a(24) =166359375a(25) =216751626a(26) =279695430a(27) =357694120a(28) =453635400a(29) =570834000