Wiener index of the grid P_n x P_n, where P_n is the path graph on n vertices.

Terms

a(0) =0a(1) =8a(2) =72a(3) =320a(4) =1000a(5) =2520a(6) =5488a(7) =10752a(8) =19440a(9) =33000a(10) =53240a(11) =82368a(12) =123032a(13) =178360a(14) =252000a(15) =348160a(16) =471648a(17) =627912a(18) =823080a(19) =1064000a(20) =1358280a(21) =1714328a(22) =2141392a(23) =2649600a(24) =3250000a(25) =3954600a(26) =4776408a(27) =5729472a(28) =6828920a(29) =8091000