A014587 Nim function for Take-a-Factorial-Game (a subtraction game).

0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2

Offset

0,3

Comments

Concerning the January 1997 dissertation of Achim Flammenkamp, his home page (currently http://wwwhomes.uni-bielefeld.de/cgi-bin/cgiwrap/achim/index.cgi) has the link shown below, and a comment that a book was published in July 1997 by Hans-Jacobs-Verlag, Lage, Germany with the title Lange Perioden in Subtraktions-Spielen (ISBN 3-932136-10-1). This is an enlarged study (more than 200 pages) of his dissertation. - N. J. A. Sloane, Jul 25 2019

References

R. K. Guy, Unsolved Problems in Number Theory, E26.

Links

Eric M. Schmidt, Table of n, a(n) for n = 0..10000

Achim Flammenkamp, Lange Perioden in Subtraktions-Spielen, Dissertation, Dept. Math., University of Bielefeld, Germany.

Formula

Conjecture: Appears to be periodic with period of length 25 = [0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 3] starting with the initial term (there is no preamble). - Michel Dekking, Jul 26 2019

This conjecture is false, because moving from 10! = 3628800 to 0 is a legal move, and so a(3628800) cannot be zero. A similar argument shows that for no value of P is this sequence periodic with period P starting at term 0 (for a(P!) cannot be zero). - Nathan Fox, Jul 28 2019.

The first counterexample to the conjecture above is a(5050) = 4. - Pontus von Brömssen, Jul 09 2022

Prog

(Sage)
def A014587(max) :
    res = []
    fact = [1]
    while fact[-1] <= max : fact.append(factorial(len(fact)))
    for i in range(max+1) :
        moves = list({res[i-f] for f in fact if f <= i})
        moves.sort()
        k = len(moves)
        mex = next((j for j in range(k) if moves[j] != j), k)
        res.append(mex)
    return res
# Eric M. Schmidt, Jul 20 2013, corrected Eric M. Schmidt, Apr 24 2019

Crossrefs

Cf. A014586-A014589, A355556.

Sequence in context: A346698 A352515 A181347 * A354388 A025658 A025673

Adjacent sequences: A014584 A014585 A014586 * A014588 A014589 A014590

Keyword

nonn

Author

Achim Flammenkamp

Status

approved