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A066158
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Number of fixed polyominoes with n cells and tree-like structure.
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11
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1, 2, 6, 18, 55, 174, 570, 1908, 6473, 22202, 76886, 268352, 942651, 3329608, 11817582, 42120340, 150682450, 540832274, 1946892842, 7027047848, 25424079339, 92185846608, 334925007128, 1219054432490, 4444545298879, 16229462702152, 59347661054364
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Computed by a modified version of the program used for A065068.
Aleksandrowicz and Barequet (2011) confirm first 27 terms. [Gill Barequet, May 25 2011]
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REFERENCES
| G. Aleksandrowicz and G. Barequet, Parallel enumeration of lattice animals, Proc. 5th Int. Frontiers of Algorithmics Workshop, Zhejiang, China, Lecture Notes in Computer Science, 6681, Springer-Verlag, 90-99, May 2011.
I. Jensen, Enumerations of lattice animals and trees, arXiv:cond-mat/0007239.
N. Madras, C. E. Soteros, S. G. Whittington, J. L. Martin, M. F. Sykes et al., The free energy of a collapsing branched polymer, J. Phys. A: Math. Gen. 23 (1990) 5327-5350
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LINKS
| I. Jensen, Table of n, a(n) for n = 1..44 [From the arXiv paper]
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CROSSREFS
| Cf. A001168 (fixed polyominoes), A019441 (coefficients of g.f. related to this sequence), A118356 / A191094 / A191095 / A191096 / A191097 / A191098 (fixed tree-like polycubes in 3, 4, 5, 6, 7, and 8 dimensions, resp.).
Sequence in context: A004529 A000778 A006725 * A148456 A148457 A182881
Adjacent sequences: A066155 A066156 A066157 * A066159 A066160 A066161
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KEYWORD
| nonn
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AUTHOR
| Jan Kristian Haugland (jankrihau(AT)hotmail.com), Dec 13 2001
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EXTENSIONS
| Added a(18) and a(19) from Madras et al. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 08 2006
Terms from a(20) on added by N. J. A. Sloane (njas(AT)research.att.com), Nov 05 2008, from the Jensen paper.
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