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A045821
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Numerical distance between m-th and (n+m)-th circles in a loxodromic sequence of circles in which each 4 consecutive circles touch.
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-1, 1, 1, 1, 7, 17, 49, 145, 415, 1201, 3473, 10033, 28999, 83809, 242209, 700001, 2023039, 5846689, 16897249, 48833953, 141132743, 407881201, 1178798545, 3406791025, 9845808799, 28454915537, 82236232177, 237667122001
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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REFERENCES
| Coxeter, H.S.M., 1998, Numerical distances among the circles in a loxodromic sequence, Nieuw Arch. Wisk, 16, pp. 1-9.
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FORMULA
| a(n)=2(a(n-1)+a(n-2)+a(n-3))-a(n-4). Also a(n)=Sum{v=0 to [ n/2 ]} C(n, 2v)*f(n-v-2) where f(m) is the m-th Fibonacci number.
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CROSSREFS
| Cf. A027674.
Sequence in context: A110097 A179262 A018672 * A115914 A094534 A081632
Adjacent sequences: A045818 A045819 A045820 * A045822 A045823 A045824
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KEYWORD
| sign
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AUTHOR
| C. L. Mallows (colinm(AT)research.avayalabs.com)
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EXTENSIONS
| Reference and formulae from Floor van Lamoen (fvlamoen(AT)hotmail.com)
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