Detour index of the n-triangular grid graph.

Terms

a(0) =0a(1) =6a(2) =69a(3) =399a(4) =1467a(5) =4197a(6) =10203a(7) =22047a(8) =43557a(9) =80187a(10) =139422a(11) =231228a(12) =368547a(13) =567837a(14) =849657a(15) =1239297a(16) =1767453a(17) =2470947a(18) =3393492a(19) =4586502a(20) =6109947a(21) =8033253a(22) =10436247a(23) =13410147a(24) =17058597a(25) =21498747a(26) =26862378a(27) =33297072a(28) =40967427a(29) =50056317