

A001573


Another approximation to A000084(n).
(Formerly M1190 N0460)


2



1, 2, 4, 9, 23, 63, 177, 514, 1527, 4625, 14230, 44357, 139779, 444558, 1425151, 4600339, 14939849, 48778197, 160019885, 527200711
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OFFSET

1,2


COMMENTS

Appears to have been calculated with very low precision. A093156 is a better version.  Pab Ter (pabrlos(AT)yahoo.com), May 11 2004


REFERENCES

J. Riordan and C. E. Shannon, The number of twoterminal seriesparallel networks, J. Math. Phys., 21 (1942), 8393. Reprinted in Claude Elwood Shannon: Collected Papers, edited by N. J. A. Sloane and A. D. Wyner, IEEE Press, NY, 1993, pp. 560570.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..20.
J. Riordan and C. E. Shannon, The number of twoterminal seriesparallel networks (annotated scanned copy)


CROSSREFS

Cf. A000084, A058585.
Sequence in context: A127384 A337721 A058585 * A135307 A000083 A092668
Adjacent sequences: A001570 A001571 A001572 * A001574 A001575 A001576


KEYWORD

nonn,more


AUTHOR

N. J. A. Sloane


STATUS

approved



