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Search: id:A055780
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| A055780 |
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Number of symmetric types of (3,2n)-hypergraphs under action of complementing group C(3,2). |
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1
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| 1, 7, 14, 35, 57, 98, 140, 210, 281, 385, 490, 637, 785, 980, 1176, 1428, 1681, 1995, 2310, 2695, 3081, 3542, 4004, 4550, 5097, 5733, 6370, 7105, 7841, 8680, 9520, 10472, 11425, 12495, 13566, 14763, 15961, 17290, 18620, 20090, 21561, 23177
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f. : -(x^8-9*x^6-5*x^2-1)/(1-x^2)^2/(1-x^4)/(1-x^8).
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EXAMPLE
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There are 7 symmetric (3,2)-hypergraphs under action of complementing group C(3,2): {{1,2},{1,2,3}}, {{1,3},{1,2,3}}, {{1,2},{1,3}}, {{2,3},{1,2,3}}, {{1,2},{2,3}}, {{1,3},{2,3}}, {{1},{2,3}}.
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MAPLE
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gf := -(x^8-9*x^6-5*x^2-1)/(1-x^2)^2/(1-x^4)/(1-x^8): s := series(gf, x, 200): for i from 0 to 200 by 2 do printf(`%d, `, coeff(s, x, i)) od:
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CROSSREFS
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Adjacent sequences: A055777 A055778 A055779 this_sequence A055781 A055782 A055783
Sequence in context: A058530 A134384 A084382 this_sequence A161814 A067048 A098328
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KEYWORD
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nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 13 2000
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 13 2000
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