Detour index of the n X n X n grid graph.

Terms

a(0) =0a(1) =184a(2) =8788a(3) =126016a(4) =953312a(5) =4980744a(6) =20000844a(7) =66781696a(8) =192914176a(9) =498751000a(10) =1176318500a(11) =2576159424a(12) =5295012768a(13) =10321114216a(14) =19204598812a(15) =34338770944a(16) =59257739264a(17) =99137135736a(18) =161273290356a(19) =255920008000a(20) =397011388000a(21) =603492894664a(22) =900354295148