4-dimensional pyramidal numbers: a(n) = n^2*(n^2-1)/12.

Terms

a(0) =0a(1) =0a(2) =1a(3) =6a(4) =20a(5) =50a(6) =105a(7) =196a(8) =336a(9) =540a(10) =825a(11) =1210a(12) =1716a(13) =2366a(14) =3185a(15) =4200a(16) =5440a(17) =6936a(18) =8721a(19) =10830a(20) =13300a(21) =16170a(22) =19481a(23) =23276a(24) =27600a(25) =32500a(26) =38025a(27) =44226a(28) =51156a(29) =58870