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A121134
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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, 5, 11, 30, 72, 182, 434, 1048, 2456, 5752, 13240, 30336, 68736, 154912, 346400, 770688, 1704576, 3753344, 8226176, 17959936, 39062528, 84679168, 182983168, 394278912, 847263744, 1816164352, 3883956224, 8288010240, 17649696768
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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REFERENCES
| 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
| 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: A121134 := proc(n) Ifunc(n, 2, 5) ; end: for n from 2 to 80 do printf("%d, ", A121134(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 07 2008]
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CROSSREFS
| Sequence in context: A092764 A176637 A059075 * A144959 A131347 A079225
Adjacent sequences: A121131 A121132 A121133 * A121135 A121136 A121137
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Aug 13 2006
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EXTENSIONS
| Extended beyond a(10) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 07 2008
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