cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A014588 Nim function for Take-a-Fibonacci-Game (a subtraction game).

Original entry on oeis.org

0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 0, 1, 2
Offset: 0

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Author

Keywords

Comments

This game is also called Fibonacci nim, but there is also a different game with the same name. Its winning positions (the indexes of zeros in this sequence) are A001581 and its (much sparser) odd winning positions are A120904. - David Eppstein, Jun 14 2018
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.
  • David L. Silverman, Your Move, McGraw Hill, 1971, page 211. Reprinted by Dover Books, 1991 (mentions this game).

Crossrefs

Programs

  • Sage
    def A014588(max) :
        res = []
        for i in range(max+1) :
            moves = list({res[i-f] for f in fibonacci_xrange(1,i+1)})
            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

A355556 a(n) is the smallest position in the subtract-a-factorial game for which the value of the Sprague-Grundy function (or nim-value) is n.

Original entry on oeis.org

0, 1, 2, 6, 5050, 5056, 5064, 40520, 40696, 630373, 40348521, 483383076, 6302798387
Offset: 0

Views

Author

Pontus von Brömssen, Jul 09 2022

Keywords

Examples

			a(3) = 6, because the smallest k for which A014587(k) = 3 is k = 6.
		

Crossrefs

Programs

  • C
    See Links section.

Extensions

a(11)-a(12) from Rémy Sigrist, Jul 09 2022

A355557 a(n) is the smallest position in the subtract-a-prime game for which the value of the Sprague-Grundy function (or nim-value) is n.

Original entry on oeis.org

0, 2, 4, 6, 8, 19, 21, 23, 43, 48, 67, 156
Offset: 0

Views

Author

Pontus von Brömssen, Jul 09 2022

Keywords

Comments

a(12) > 32452842 (if it exists). See A014589.
a(12) > 10^9 if it exists. - Bert Dobbelaere, Apr 09 2024

Examples

			a(5) = 19, because the smallest k for which A014589(k) = 5 is k = 19.
		

Crossrefs

Showing 1-3 of 3 results.