a(n) = n * (n+1)^2 * (3*n^2 + 4*n + 2) / 12.

Terms

a(0) =0a(1) =3a(2) =33a(3) =164a(4) =550a(5) =1455a(6) =3283a(7) =6608a(8) =12204a(9) =21075a(10) =34485a(11) =53988a(12) =81458a(13) =119119a(14) =169575a(15) =235840a(16) =321368a(17) =430083a(18) =566409a(19) =735300a(20) =942270a(21) =1193423a(22) =1495483a(23) =1855824a(24) =2282500a(25) =2784275a(26) =3370653a(27) =4051908a(28) =4839114a(29) =5744175