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A131600 Number of different configurations of an n-block of a shift space with k symbols where each symbol but the first must appear isolated and separated from others by a block of length at least m made of first symbols. For k=2 is the number of different configurations of an n-bits string where each 1 is isolated and separated by at least m zeros. 0
19, 37, 55, 397, 1063, 2053, 9199, 28333, 65287, 230869, 740863, 1916029 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

a(n+1)/a(n) -> 3.

REFERENCES

math:archiv:0708.4370

LINKS

R. Tonelli, Fibonacci-like sequences and shift spaces.

FORMULA

a(n) = a(n-1) + (k-1)*a(n-m-1), where k=19, m=2.

G.f.: -x*(19+18*x+18*x^2)/(3*x-1)/(6*x^2+2*x+1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 14 2007

CROSSREFS

Cf. A000045, A000930.

Sequence in context: A139313 A109639 A161705 * A175546 A162471 A124268

Adjacent sequences:  A131597 A131598 A131599 * A131601 A131602 A131603

KEYWORD

easy,nonn

AUTHOR

R. Tonelli (roberto.tonelli(AT)dsf.unica.it), Aug 31 2007

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Last modified February 17 00:09 EST 2012. Contains 205978 sequences.