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Search: id:A058534
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| A058534 |
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A 3-way generalization of series-parallel networks with n unlabeled edges. |
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+0
3
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| 0, 1, 3, 6, 15, 36, 99, 270, 783, 2298, 6936, 21204, 65895, 206862, 656253, 2098602, 6761028, 21917364, 71450229, 234070806, 770216253, 2544458592, 8435990916, 28060099692, 93612265143, 313153860210, 1050194570445, 3530080085868
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Compare the combstruct construction here with that for A000084.
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MAPLE
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spec := [ N, {N=Union(Z, S, P, Q), S=Set(Union(Z, P), card>=2), P=Set(Union(Z, Q), card>=2), Q=Set(Union(Z, S), card>=2)} ]; [seq(combstruct[count](spec, size=n), n=0..40)]; # N = A058534, S=A000669
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CROSSREFS
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Cf. A000084, A058540, A000669, A058561.
Adjacent sequences: A058531 A058532 A058533 this_sequence A058535 A058536 A058537
Sequence in context: A126971 A005043 A099323 this_sequence A063778 A087124 A086326
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KEYWORD
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nonn
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AUTHOR
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njas, Dec 24 2000
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