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Search: id:A121135
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| A121135 |
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Numbers of isomers of unbranched a-4-catapolypentagons - see Brunvoll reference for precise definition. |
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1
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| 1, 2, 8, 22, 74, 208, 598, 1600, 4248, 10880, 27512, 68096, 166528, 401408, 957728, 2260992, 5292672, 12288000, 28329344, 64880640, 147721216, 334495744, 753670656, 1690304512, 3774887936, 8396996608, 18610157568, 41104179200
(list; graph; listen)
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OFFSET
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3,2
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REFERENCES
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J. Brunvoll, S. J. Cyvin and B. N. Cyvin, Isomer enumeration of polygonal systems..., J. Molec. Struct. (Theochem), 364 (1996), 1-13.
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MAPLE
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H := proc(r, alpha, q) local rhalf, alphahalf ; rhalf := floor(r/2) ; alphahalf := floor(alpha/2) ; (binomial(rhalf-1, alphahalf-1)*(q-3)+binomial(rhalf-1, alphahalf))*(q-3)^(rhalf-alphahalf-1) ; end: J := proc(r, alpha, q) (binomial(r-2, alpha-2)*(q-3)^2+2*binomial(r-2, alpha-1)*(q-3)+binomial(r-2, alpha))*(q-3)^(r-alpha-2) ; end: Ifunc := proc(r, alpha, q) J(r, alpha, q)/4+binomial(2, r-alpha)/4+ (1+(-1)^(r+alpha)+(1+(-1)^alpha)*(1-(-1)^r)/2)*H(r, alpha, q)/4 ; end: A121135 := proc(n) Ifunc(n, 3, 5) ; end: for n from 3 to 80 do printf("%d, ", A121135(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 07 2008]
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CROSSREFS
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Cf. A121133. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 07 2008]
Sequence in context: A089586 A045695 A106053 this_sequence A072929 A053958 A151356
Adjacent sequences: A121132 A121133 A121134 this_sequence A121136 A121137 A121138
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Aug 13 2006
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EXTENSIONS
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Extended beyond a(10) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 07 2008
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