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A033623 Grundy function for turn-at-most-4-coins game. 5
1, 2, 4, 8, 15, 16, 32, 51, 64, 85, 106, 128, 150, 171, 219, 237, 247, 256, 279, 297, 455, 512, 537, 557, 594, 643, 803, 863, 998, 1024, 1051, 1070, 1112, 1169, 1333, 1345, 1620, 1866, 2048, 2076, 2085, 2185, 2372 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

E. R. Berlekamp, J. H. Conway and R. K. Guy, Winning Ways, Table 3, page 433.

LINKS

Table of n, a(n) for n=1..43.

FORMULA

a(n)=smallest natural not the exclusive-or of at most three a(k) for k<n.

MATHEMATICA

Clear[a]; a[1] = 1; a[n_] := a[n] = (xor = BitXor @@@ Subsets[Array[a, n-1], 3] // Union ; r = Range[0, m = Last[xor]]; cp = Complement[r, xor]; If[cp == {}, m+1, First[cp]]); Table[a[n], {n, 1, 43}] (* Jean-Fran├žois Alcover, Jan 09 2013 *)

CROSSREFS

Cf. A000069, A054016, A054043, etc.

Sequence in context: A140117 A039743 A070008 * A094398 A277728 A287163

Adjacent sequences:  A033620 A033621 A033622 * A033624 A033625 A033626

KEYWORD

nonn,nice,easy

AUTHOR

David A. Madore

EXTENSIONS

More terms from N. J. A. Sloane Apr 29, 2000

STATUS

approved

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Last modified October 15 15:03 EDT 2019. Contains 328030 sequences. (Running on oeis4.)