a(n) = n*(2*n+1)^2.

Terms

a(0) =0a(1) =9a(2) =50a(3) =147a(4) =324a(5) =605a(6) =1014a(7) =1575a(8) =2312a(9) =3249a(10) =4410a(11) =5819a(12) =7500a(13) =9477a(14) =11774a(15) =14415a(16) =17424a(17) =20825a(18) =24642a(19) =28899a(20) =33620a(21) =38829a(22) =44550a(23) =50807a(24) =57624a(25) =65025a(26) =73034a(27) =81675a(28) =90972a(29) =100949