Sums of groups in A075639.

Terms

a(0) =1a(1) =9a(2) =21a(3) =70a(4) =185a(5) =354a(6) =625a(7) =1012a(8) =1555a(9) =2250a(10) =3125a(11) =4284a(12) =5627a(13) =7252a(14) =9205a(15) =11378a(16) =14075a(17) =17122a(18) =20385a(19) =24386a(20) =28805a(21) =33582a(22) =38741a(23) =45026a(24) =51641a(25) =58952a(26) =66609a(27) =75384a(28) =84217a(29) =95020