4-dimensional pyramidal numbers: a(n) = (3*n+1)*binomial(n+2, 3)/4. Also Stirling2(n+2, n).

Terms

a(0) =0a(1) =1a(2) =7a(3) =25a(4) =65a(5) =140a(6) =266a(7) =462a(8) =750a(9) =1155a(10) =1705a(11) =2431a(12) =3367a(13) =4550a(14) =6020a(15) =7820a(16) =9996a(17) =12597a(18) =15675a(19) =19285a(20) =23485a(21) =28336a(22) =33902a(23) =40250a(24) =47450a(25) =55575a(26) =64701a(27) =74907a(28) =86275a(29) =98890