A261990 Color of the cell Langton's Ant touches on its n-th step before the color is changed by the ant; 0=white, 1=black.

0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0

Offset

0

Comments

The ant starts from a completely white grid.

There are never more than four 0's or 1's in a row because four identical turns will circle back into the same cell, which will have since changed.

The sequence begins repeating at the 9977th step, in a cycle of length 104.

Links

Aaron David Fairbanks, Table of n, a(n) for n = 0..10287

Wikipedia, Langton's Ant

Example

On the 0th step, the ant lands on a white square and turns it black. On the 1st step, it lands on another white square. On the 4th step, it lands on a black square, etc.

Crossrefs

Cf. A126978.

Sequence in context: A093957 A283317 A188041 * A144601 A188009 A353812

Adjacent sequences: A261987 A261988 A261989 * A261991 A261992 A261993

Keyword

easy,nonn

Author

Aaron David Fairbanks, Sep 07 2015

Status

approved