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A006021 The game of contours.
(Formerly M0409)
0
0, 1, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2, 3, 1, 4, 3, 2, 0, 5, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

REFERENCES

E. R. Berlekamp, J. H. Conway and R. K. Guy, Winning Ways, Academic Press, NY, 2 vols., 1982, see p. 553.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..82.

FORMULA

a(0) = 0, b(1) = 0, a(n) = mex({a(s) ^ b(t): s+t = n-1 and s>0} union {b(s) + b(t): s+t = n-1}), b(n) = mex({a(s) ^ b(t): s+t = n-1 and s>0}) with ^ denoting bitwise addition. - Sean A. Irvine, Dec 14 2016

a(n+8) = a(n) for n >= 6. - Sean A. Irvine, Dec 14 2016

CROSSREFS

Sequence in context: A011857 A242360 A299927 * A002186 A125936 A243614

Adjacent sequences:  A006018 A006019 A006020 * A006022 A006023 A006024

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Sean A. Irvine, Dec 14 2016

STATUS

approved

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Last modified February 16 18:53 EST 2019. Contains 320165 sequences. (Running on oeis4.)