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Search: id:A036757
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| A036757 |
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Number of tree-like heptagonal systems. |
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+0
1
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| 1, 1, 2, 7, 26, 126, 640, 3559, 20366, 120535, 727292, 4468614, 27842644, 175644673, 1119847820, 7207062667, 46769169830, 305762838483, 2012363156332, 13324398048658, 88709165046956, 593555082569368, 3989727169508528
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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J. Brunvoll et al., Enumeration of tree-like octagonal systems, J. Math. Chem., 21 (1997), 193-196.
S. J. Cyvin et al., Enumeration of tree-like octagonal systems: catapolyoctagons, ACH Models in Chem. 134 (1997), 55-70.
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FORMULA
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G.f.: (x^2/54)[5+12x-27x^2+16x^3+3x^4+(1/4)(1-8x+4x^2)^(3/2)- (3/4)(7+12x+2x^2)(1-8x^2+4x^4)^(1/2)].
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CROSSREFS
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Sequence in context: A081566 A141203 A096803 this_sequence A068870 A005519 A037381
Adjacent sequences: A036754 A036755 A036756 this_sequence A036758 A036759 A036760
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KEYWORD
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nonn,easy
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AUTHOR
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njas
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 28 2004
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