%I #5 Jul 27 2015 19:23:03
%S 0,0,0,0,0,0,1,1,0,0,0,0,0,0,16,28,0,0,0,0,0,0,1190,2108,0,0,0,0,0,0
%N Number of possibly-self-intersecting walks that it is possible for an accelerating ant to produce with n steps (rotations & reflections not included). On step 1 the ant moves forward 1 unit, then turns left or right and proceeds 2 units, then turns left or right until at the end of its n-th step it arrives back at its starting place.
%C Accelerating ant walks can only arrive back at the starting place if the number of moves is -1 or 0 mod(8).
%e a(7) = 1 because of the following solution:
%e 655555XXX
%e 6XXXX4XXX
%e 6XXXX4XXX
%e 6XXXX4XXX
%e 6XXXX4333
%e 6XXXXXXX2
%e 777777712
%e where the ant starts at the "1" and moves right 1 space, up 2 spaces and so on...
%Y Cf. A101856.
%K nice,nonn
%O 1,15
%A _Gordon Hamilton_, Jan 27 2005