a(n) = (8*n - 3)*(4*n - 1)*(8*n^2 - 5*n + 1).

Terms

a(0) =3a(1) =60a(2) =2093a(3) =13398a(4) =47415a(5) =123728a(6) =268065a(7) =512298a(8) =894443a(9) =1458660a(10) =2255253a(11) =3340670a(12) =4777503a(13) =6634488a(14) =8986505a(15) =11914578a(16) =15505875a(17) =19853708a(18) =25057533a(19) =31222950a(20) =38461703a(21) =46891680a(22) =56636913a(23) =67827578a(24) =80599995a(25) =95096628a(26) =111466085a(27) =129863118a(28) =150448623