Wiener index of the graph of nodes (i,j) of the square lattice such that abs(i) + abs(j) <= n.

Terms

a(0) =0a(1) =16a(2) =192a(3) =1008a(4) =3504a(5) =9504a(6) =21840a(7) =44576a(8) =83232a(9) =145008a(10) =239008a(11) =376464a(12) =570960a(13) =838656a(14) =1198512a(15) =1672512a(16) =2285888a(17) =3067344a(18) =4049280a(19) =5268016a(20) =6764016a(21) =8582112a(22) =10771728a(23) =13387104a(24) =16487520a(25) =20137520a(26) =24407136a(27) =29372112a(28) =35114128a(29) =41721024