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A038620
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Growth function of an infinite cubic graph (no of nodes at distance n from fixed node).
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1
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1, 3, 6, 12, 24, 35, 48, 69, 86, 108, 138, 161, 192, 231, 260, 300, 348, 383, 432, 489, 530, 588, 654, 701, 768, 843, 896, 972, 1056, 1115, 1200, 1293, 1358, 1452, 1554, 1625, 1728, 1839
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| J. K. Haugland, Classification of certain subgraphs of the 3-dimensional grid., J. Graph Theory, 42 (2003), 34-60.
J. K. Haugland, Illustration
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FORMULA
| a(0) = 1, a(1) = 3, a(2) = 6; a(n) = 4n^2 / 3, n >= 3 and n == 0 (mod 3); a(n) = (4n^2 + n + 4) / 3, n >= 3 and n == 1 (mod 3); a(n) = (4n^2 - n + 10) / 3, n >= 3 and n == 2 (mod 3).
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CROSSREFS
| Cf. A038621.
Sequence in context: A097979 A173216 A003204 * A039695 A079079 A132974
Adjacent sequences: A038617 A038618 A038619 * A038621 A038622 A038623
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KEYWORD
| nonn
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AUTHOR
| Jan Kristian Haugland (jankrihau(AT)hotmail.com)
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EXTENSIONS
| Links corrected by Jan Kristian Haugland (admin(AT)neutreeko.net), Mar 01 2009
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