Volume of the Johnson square pyramid (rounded down) with all the edge lengths equal to n.

Terms

a(0) =0a(1) =1a(2) =6a(3) =15a(4) =29a(5) =50a(6) =80a(7) =120a(8) =171a(9) =235a(10) =313a(11) =407a(12) =517a(13) =646a(14) =795a(15) =965a(16) =1158a(17) =1374a(18) =1616a(19) =1885a(20) =2182a(21) =2509a(22) =2867a(23) =3258a(24) =3682a(25) =4142a(26) =4639a(27) =5174a(28) =5748a(29) =6363