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A072404 Denominator of the Reingold-Tarjan sequence, numerator=A072403. 1
1, 3, 9, 9, 27, 27, 3, 27, 81, 81, 27, 81, 81, 9, 81, 81, 243, 243, 27, 243, 243, 81, 243, 243, 81, 243, 243, 27, 243, 243, 81, 243, 729, 729, 243, 729, 729, 81, 729, 729, 243, 729, 729, 243, 729, 729, 9, 729, 729, 243, 729, 729, 243, 729, 729, 81 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

The the Reingold-Tarjan sequence is based on the following function defined on even positive integers and range of the rational numbers:

f(2*n) = if n is even then 2*f(n)/3 else (f(n+1)+f(n-1))/3 for n>1, f(2*1)=1.

f(2*n) = A072403(n)/a(n) for n>1, A072403(1)=1 and a(1)=1.

REFERENCES

J.-P. Allouche and J. Shallit, The ring of k-regular sequences (Example 33), Theoretical Computer Science, 98 (1992), 163-197.

E. M. Reingold and R. E. Tarjan, On a greedy heuristic for complete matching, SIAM J. Computing 10 (1981), 676-681.

LINKS

J.-P. Allouche and J. Shallit, The ring of k-regular sequences, Theoretical Computer Sci., 98 (1992), 163-197.

CROSSREFS

Sequence in context: A207221 A206700 A162349 * A125824 A203558 A038227

Adjacent sequences:  A072401 A072402 A072403 * A072405 A072406 A072407

KEYWORD

nonn,frac

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 16 2002

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Last modified February 16 06:46 EST 2012. Contains 205867 sequences.