a(n) = n*(n + 1)*(7*n + 5)/6.

Terms

a(0) =0a(1) =4a(2) =19a(3) =52a(4) =110a(5) =200a(6) =329a(7) =504a(8) =732a(9) =1020a(10) =1375a(11) =1804a(12) =2314a(13) =2912a(14) =3605a(15) =4400a(16) =5304a(17) =6324a(18) =7467a(19) =8740a(20) =10150a(21) =11704a(22) =13409a(23) =15272a(24) =17300a(25) =19500a(26) =21879a(27) =24444a(28) =27202a(29) =30160