login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A038219 A maximally unpredictable sequence. 8
0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1

COMMENTS

Comment from Christopher Carl Heckman, Feb 10 2005: The sequence starts 0,1,0 and continues according to the following rule: find the longest sequence at the end that has occurred at least once previously. If there are more than one previous occurrences select the last one. The next digit of the sequence is the opposite of the one following the previous occurrence.

REFERENCES

A. Ehrenfeucht and J. Mycielski, A pseudorandom sequence - how random is it?, Amer. Math. Monthly, 99 (1992), 373-375.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..5000

K. Sutner, The Ehrenfeucht-Mycielski sequence

Terry McConnell, The Ehrenfeucht-Mycielski Sequence

PROG

(Haskell)

a038219 n = a038219_list !! n

a038219_list = 0 : f [0] where

   f us = a' : f (us ++ [a']) where

        a' = b $ reverse $ map (`splitAt` us) [0..length us - 1] where

           b ((xs, ys):xyss) | vs `isSuffixOf` xs = 1 - head ys

                            | otherwise          = b xyss

        vs = fromJust $ find (`isInfixOf` init us) $ tails us

-- Reinhard Zumkeller, Dec 05 2011

CROSSREFS

Cf. A007061 (1, 2 version).

Cf. A201881 (run lengths).

Sequence in context: A189572 A244735 A245938 * A172486 A189668 A215530

Adjacent sequences:  A038216 A038217 A038218 * A038220 A038221 A038222

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane, Mira Bernstein

EXTENSIONS

More terms from Joshua Zucker, Aug 11 2006

Offset changed by Reinhard Zumkeller, Dec 11 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified October 22 21:52 EDT 2014. Contains 248411 sequences.