A346401 a(n) is the minimum number of pebbles such that any assignment of those pebbles on a complete graph with n vertices is a next-player winning game in the two-player impartial (3, 2) pebbling game.
13, 21, 15, 21, 17, 25, 21, 29, 25, 33, 29, 37, 33, 41, 37, 45, 41, 49, 45, 53, 49, 57
Offset: 3
Examples
For n=6, a(6)=21 is the least number of pebbles for which every (3,2) game on K_6 is a next-player winning game regardless of assignment. For n=7, a(7)=17 is the least number of pebbles for which every (3,2) game on K_7 is a next-player winning game regardless of assignment.
References
- E. R. Berlekamp, J. H. Conway, and R. K. Guy, Winning Ways for Your Mathematical Plays, Vol. 1, CRC Press, 2001.
Links
- E. Fiorini, M. Lind, A. Woldar, and T. W. H. Wong,Characterizing Winning Positions in the Impartial Two-Player Pebbling Game on Complete Graphs, Journal of Integer Sequences, 24(6), 2021.
Programs
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Mathematica
remove = 3; add = 2; (*Given n and m,list all possible assignments.*) alltuples[n_, m_] := IntegerPartitions[m + n, {n}] - 1; (*Given an assignment,list all resultant assignments after one pebbling move; only work for n>=3.*) pebblemoves[config_] := Block[{n, temp}, n = Length[config]; temp = Table[config, {i, n (n - 1)}] + Permutations[Join[{-remove, add}, Table[0, {i, n - 2}]]]; temp = Select[temp, Min[#] >= 0 &]; temp = ReverseSort[DeleteDuplicates[ReverseSort /@ temp]]]; (*Given n and m,list all assignments that are P-games.*) Plist = {}; plist[n_, m_] := Block[{index, tuples}, While[Length[Plist] < n, index = Length[Plist]; AppendTo[Plist, {{Join[{1}, Table[0, {i, index}]]}}]]; Do[AppendTo[Plist[[n]], {}]; tuples = alltuples[n, i]; Do[If[Not[IntersectingQ[pebblemoves[tuples[[j]]], If[i > (remove - add), Plist[[n, i - (remove - add)]], {}]]], AppendTo[Plist[[n, i]], tuples[[j]]]], {j, Length[tuples]}], {i, Length[Plist[[n]]] + 1, m}]; Plist[[n, m]]]; Do[m = 1; While[plist[n, m] != {}, m++]; Print[" n=", n, " m=", m], {n, 3, 24}]
Formula
a(n) = 2n+3 when n >= 7 is odd (conjectured).
a(n) = 2n+9 when n >= 6 is even (conjectured).
Comments