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A016031 De Bruijn's sequence: 2^(2^(n-1) - n): ways of arranging 2^n bits in circle so all 2^n consecutive strings of length n are distinct. +0
3
1, 1, 2, 16, 2048, 67108864, 144115188075855872, 1329227995784915872903807060280344576, 226156424291633194186662080095093570025917938800079226639565593765455331328 (list; graph; listen)
OFFSET

1,3

COMMENT

Sequence corresponds also to the largest number that may be determined by asking no more than 2^(n-1) - 1 questions("Yes"-or-"No" answerable)with lying allowed at most once. - Lekraj Beedassy (blekraj(AT)yahoo.com), Jul 15 2002

Number of Ouroborean rings for binary n-tuplets. - Lekraj Beedassy (blekraj(AT)yahoo.com), May 06 2004

Also the number of games of Nim that are wins for the second player when the starting position is either the empty heap or heaps of sizes 1 <= t_1 < t_2 < ... < t_k < 2^(n-1) (if n is 1, the only starting position is the empty heap). E.g.: a(4) = 16: the winning positions for the second player when all the heap sizes are different and less than 2^3: (4,5,6,7), (3,5,6), (3,4,7), (2,5,7), (2,4,6), (2,3,6,7), (2,3,4,5), (1,6,7), (1,4,5), (1,3,5,7), (1,3,4,6), (1,2,5,6), (1,2,4,7), (1,2,3), (1,2,3,4,5,6,7) and the empty heap. - Kennan Shelton (kennan.shelton(AT)gmail.com), Apr 14 2006

REFERENCES

F. Harary and E. Palmer, Graphical Enumeration, (1973), p. 31.

D. J. Newman, "A variation of the Game of Twenty Question", Prob. 66-20 pp. 121-2 In Problems in Applied Mathematics, Ed. M. S. Klamkin, SIAM PA 1990.

R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Cor. 5.6.15.

I. Stewart, Game, Set and Math, pp. 50, Penguin 1991.

J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 255.

LINKS

R. Erra, N. Lygeros and N. Stewart, On Minimal Strings Containing the Elements of S(n) by Decimation; Section 5.4

Wikipedia, De Bruijn sequence

FORMULA

a(n)=2^{A000295(n-1)}. - Lekraj Beedassy (blekraj(AT)yahoo.com), Jan 17 2007

MAPLE

P:=proc(n) local i, j; for i from 1 by 1 to n do j:=2^(2^(i-1)-i); print(j); od; end: P(20); - Paolo P. Lava (ppl(AT)spl.at), May 11 2006

CROSSREFS

Sequence in context: A102103 A060597 A091479 this_sequence A001309 A132569 A165644

Adjacent sequences: A016028 A016029 A016030 this_sequence A016032 A016033 A016034

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Robert G. Wilson v (rgwv(AT)rgwv.com)

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Last modified December 10 12:37 EST 2009. Contains 170569 sequences.


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