

A058387


Number of seriesparallel networks with n unlabeled edges, multiple edges not allowed.


3



0, 1, 1, 2, 4, 8, 18, 40, 94, 224, 548, 1356, 3418, 8692, 22352, 57932, 151312, 397628, 1050992, 2791516, 7447972, 19950628, 53635310, 144664640, 391358274, 1061628772, 2887113478, 7869761108, 21497678430, 58841838912, 161356288874
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OFFSET

0,4


COMMENTS

This is a seriesparallel network: oo; all other seriesparallel networks are obtained by connecting two seriesparallel networks in series or in parallel. See A000084 for examples.


REFERENCES

J. W. Moon, Some enumerative results on seriesparallel networks, Annals Discrete Math., 33 (1987), 199226 (the sequence v_n).


LINKS

Table of n, a(n) for n=0..30.
Index entries for sequences mentioned in Moon (1987)
S. R. Finch, Seriesparallel networks
S. R. Finch, Seriesparallel networks, July 7, 2003. [Cached copy, with permission of the author]


FORMULA

A058387 = A058385 + A058386.


CROSSREFS

Cf. A058379, A058386, A058385, A000084, A000311, A000669, A006351.
Sequence in context: A000967 A288309 A096813 * A330052 A317787 A019231
Adjacent sequences: A058384 A058385 A058386 * A058388 A058389 A058390


KEYWORD

nonn,nice,easy


AUTHOR

N. J. A. Sloane, Dec 20 2000


STATUS

approved



