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Search: id:A055503
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| A055503 |
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Take n points in general position in plane; draw all lines joining them; sequence gives number of connected regions formed. |
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+0
3
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| 1, 1, 2, 7, 18, 41, 85, 162, 287, 478, 756, 1145, 1672, 2367, 3263, 4396, 5805, 7532, 9622, 12123, 15086, 18565, 22617, 27302, 32683, 38826, 45800, 53677, 62532, 72443, 83491, 95760, 109337, 124312, 140778, 158831, 178570, 200097
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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L. Comtet, Advanced Combinatorics, Reidel, 1974, Problem 1, p. 72; and Problem 8, p. 74.
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LINKS
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Author?, Title? (from Alexander Evnin (graph98(AT)yandex.ru), Dec 06 2008)
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FORMULA
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(1/8)*(n-1)*(n^3-5*n^2+18*n-8) for n>1.
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MAPLE
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A055503 := n->(1/8)*(n^4-6*n^3+23*n^2-26*n+8); [for n >1]
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CROSSREFS
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Cf. A000124.
Sequence in context: A086741 A051743 A054111 this_sequence A077802 A095151 A147611
Adjacent sequences: A055500 A055501 A055502 this_sequence A055504 A055505 A055506
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jul 10 2000
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EXTENSIONS
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a(1) changed from 0 to 1 by N. J. A. Sloane (njas(AT)research.att.com), Dec 07 2008
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