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A045902
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Catafusenes (see reference for precise definition).
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0
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1, 4, 18, 80, 355, 1580, 7066, 31772, 143645, 652860, 2981910, 13682328, 63046776, 291646860, 1353967250, 6306552800, 29464361530, 138045441260, 648449195350, 3053348997200, 14409512770575, 68143962854836, 322886537205062
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| 4-fold convolution of A002212. Convolution of A045868 with itself. - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 13 2004
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REFERENCES
| S. J. Cyvin et al., Enumeration and classification of certain polygonal systems... : annelated catafusenes, J. Chem. Inform. Comput. Sci., 34 (1994), 1174-1180.
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FORMULA
| G.f.: [1-x-sqrt(1-6x+5x^2)]^4/(16x^4). - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 13 2004
a(n)=(4/n)*sum(binomial(n, j)*binomial(2j+3, j-1), j=1..n) for n>=1. - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 25 2004
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MAPLE
| a := n->(4/n)*sum(binomial(n, j)*binomial(2*j+3, j-1), j=1..n): 1, seq(a(n), n=1..22);
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CROSSREFS
| Cf. A002212, A045868.
Sequence in context: A196810 A177755 A037965 * A090017 A104631 A106391
Adjacent sequences: A045899 A045900 A045901 * A045903 A045904 A045905
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 13 2004
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