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A101857 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. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,15

COMMENTS

Accelerating ant walks can only arrive back at the starting place if the number of moves is -1 or 0 mod(8).

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

a(7) = 1 because of the following solution:

655555XXX

6XXXX4XXX

6XXXX4XXX

6XXXX4XXX

6XXXX4333

6XXXXXXX2

777777712

where the ant starts at the "1" and moves right 1 space, up 2 spaces and so on...

CROSSREFS

Cf. A101856.

Sequence in context: A073396 A302553 A300132 * A184039 A212051 A166595

Adjacent sequences:  A101854 A101855 A101856 * A101858 A101859 A101860

KEYWORD

nice,nonn

AUTHOR

Gordon Hamilton, Jan 27 2005

STATUS

approved

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Last modified September 18 20:22 EDT 2019. Contains 327181 sequences. (Running on oeis4.)