a(n) = (2*n - 1)*(11*n^2 - 11*n + 6)/6.

Terms

a(0) =1a(1) =14a(2) =60a(3) =161a(4) =339a(5) =616a(6) =1014a(7) =1555a(8) =2261a(9) =3154a(10) =4256a(11) =5589a(12) =7175a(13) =9036a(14) =11194a(15) =13671a(16) =16489a(17) =19670a(18) =23236a(19) =27209a(20) =31611a(21) =36464a(22) =41790a(23) =47611a(24) =53949a(25) =60826a(26) =68264a(27) =76285a(28) =84911a(29) =94164