a(n) = n^2*(5*n-3)/2.

Terms

a(0) =0a(1) =1a(2) =14a(3) =54a(4) =136a(5) =275a(6) =486a(7) =784a(8) =1184a(9) =1701a(10) =2350a(11) =3146a(12) =4104a(13) =5239a(14) =6566a(15) =8100a(16) =9856a(17) =11849a(18) =14094a(19) =16606a(20) =19400a(21) =22491a(22) =25894a(23) =29624a(24) =33696a(25) =38125a(26) =42926a(27) =48114a(28) =53704a(29) =59711