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A154640
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a(n) is the number of spheres that are added in the n-th generation of Apollonian packing of three-dimensional spheres, starting with five mutually tangent spheres and using "strategy (a)" to count them (see the reference).
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1
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OFFSET
| 0,1
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COMMENTS
| In strategy (a) we do not count spheres that are generated (by reflection) from quintuples that were not generated in the previous generation.
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REFERENCES
| C. L. Mallows, Growing Apollonian packings. J. Integer Sequences 12, article 09.2.1 (2009)
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EXAMPLE
| For a(3), we apply reflection only to the 20 quintuples that were generated in the second generation, ignoring the 10 "extra" quintuples (which will appear as ABA = BAB in the third generation).
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CROSSREFS
| For other sequences relating to the 3-dimensional case, see A154638-A154645.
Sequence in context: A205882 A099921 A139470 * A154643 A186411 A127513
Adjacent sequences: A154637 A154638 A154639 * A154641 A154642 A154643
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KEYWORD
| hard,more,nonn
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AUTHOR
| Colin Mallows (colinm(AT)research.avayalabs.com), Jan 13 2009
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