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A038621
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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, 4, 10, 22, 46, 81, 129, 198, 284, 392, 530, 691, 883, 1114, 1374, 1674, 2022, 2405, 2837, 3326, 3856, 4444, 5098, 5799, 6567, 7410, 8306, 9278, 10334, 11449, 12649, 13942, 15300, 16752, 18306, 19931, 21659, 23498
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| Partial sums of A038620.
a(0) = 1, a(1) = 4, a(n) = (4 n^3 + 6 n^2 + 15 n - 9) / 9, n >= 2 and n == 0 (mod 3), (4 n^3 + 6 n^2 + 18 n - 10) / 9, n >= 2 and n == 1 (mod 3), (4 n^3 + 6 n^2 + 15 n + 4) / 9, n >= 2 and n == 2 (mod 3).
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CROSSREFS
| Sequence in context: A023628 A004798 A174622 * A078407 A033484 A099018
Adjacent sequences: A038618 A038619 A038620 * A038622 A038623 A038624
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KEYWORD
| nonn
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AUTHOR
| Jan Kristian Haugland (jankrihau(AT)hotmail.com)
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