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Search: id:A058561
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| A058561 |
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A 3-way generalization of series-parallel networks with n labeled edges. |
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+0
2
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| 0, 1, 3, 12, 78, 708, 8256, 117624, 1980096, 38456736, 846413472, 20819693568, 565998548352, 16852047061632, 545372109629184, 19061178127458816, 715541912895773184, 28713061759257037824, 1226513716981332031488
(list; graph; listen)
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OFFSET
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0,3
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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)}, labeled ]; [seq(combstruct[count](spec, size=n), n=0..40)]; # N = A058561, S=A000311
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CROSSREFS
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Cf. A058534, A000311, A006351.
Sequence in context: A121421 A136735 A108043 this_sequence A058107 A023879 A084565
Adjacent sequences: A058558 A058559 A058560 this_sequence A058562 A058563 A058564
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KEYWORD
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nonn
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AUTHOR
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njas, Dec 26 2000
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