A110471 - OEIS

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A110471

Prime analog of Baum-Sweet sequence: a(n) = 1 if binary representation of n contains no block of consecutive zeros of exactly prime length; otherwise a(n) = 0.

1, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0

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OFFSET

0,1

REFERENCES

J.-P. Allouche and J. Shallit, Automatic Sequences, Cambridge Univ. Press, 2003, p. 157.

LINKS

Table of n, a(n) for n=0..104.

J.-P. Allouche, Finite Automata and Arithmetic, Séminaire Lotharingien de Combinatoire, B30c (1993), 23 pp.

EXAMPLE

a(4) = 0 because 4 (base 2) = 100, which has 2 (prime) consecutive zeros.

a(8) = 0 because 8 (base 2) = 1000, which has 3 (prime) consecutive zeros.

a(9) = 0 because 9 (base 2) = 1001, which has 2 (prime) consecutive zeros.

a(16) = 1 because 16 (base 2) = 10000, which has 4 (composite) consecutive zeros, even though there are subblocks of zeros of lengths 2 and 3.

a(32) = 0 because 32 (base 2) = 100000, which has 5 (prime) consecutive zeros.

MATHEMATICA

f[n_] := If[Or @@ (First[ # ] == 0 && PrimeQ[Length[ # ]] &) /@ Split[IntegerDigits[n, 2]], 0, 1]; Table[f[n], {n, 0, 120}] (* Ray Chandler, Sep 16 2005 *)

CROSSREFS

Cf. A037011, A086747, A110472, A110474.

Sequence in context: A336923 A239681 A054524 * A360116 A255339 A174854

Adjacent sequences: A110468 A110469 A110470 * A110472 A110473 A110474

KEYWORD

base,easy,nonn

AUTHOR

Jonathan Vos Post, Sep 07 2005

EXTENSIONS

Extended by Ray Chandler, Sep 16 2005

STATUS

approved