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A045635
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Catafusenes (see references for precise definition).
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0
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0, 0, 1, 9, 57, 315, 1629, 8127, 39718, 191754, 919035, 4385799, 20879100, 99276840, 471848195, 2242864575, 10665998760, 50757180840, 241743946635, 1152434818755, 5499250360025, 26268118117731, 125602004765391
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OFFSET
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1,4
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COMMENTS
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The sequence without the initial 0's is the 3-fold convolution of A002212(n), (n=1,2,...). - Emeric Deutsch, Mar 13 2004
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REFERENCES
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B. N. Cyvin et al., A class of polygonal systems representing polycyclic conjugated hydrocarbons ..., Monat. f. Chemie, 125 (1994), 1327-1337.
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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LINKS
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Table of n, a(n) for n=1..23.
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FORMULA
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G.f. = (zM)^3, where M=[1-3z-sqrt(1-6z+5z^2)]/(2z^2). - Emeric Deutsch, Mar 13 2004
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MAPLE
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Z:=(1-8*z+24*z^2-16*z^3-(1-6*z+8*z^2)*sqrt(1-6*z+5*z^2))/2: Zser:=series(Z, z=0, 32): seq(coeff(Zser, z, n), n=4..26); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 01 2007
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CROSSREFS
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Cf. A002212.
Sequence in context: A192054 A045720 A014916 * A026896 A080961 A163919
Adjacent sequences: A045632 A045633 A045634 * A045636 A045637 A045638
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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More terms from Emeric Deutsch, Mar 13 2004
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STATUS
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approved
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