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A208453
Meandric numbers for a river crossing up to 7 parallel roads at n points.
18
1, 1, 2, 4, 10, 23, 63, 155, 447, 1150, 3433, 9118, 27923, 75981, 237379, 658380, 2090519, 5888530, 18951534, 54069881, 176020213, 507632647, 1668910009, 4857449082, 16106998656, 47253245257, 157874165288, 466367068388, 1568587476660, 4661900731148, 15773729508730
OFFSET
0,3
COMMENTS
Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 7 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.
LINKS
CROSSREFS
Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Sequence in context: A208126 A370646 A208452 * A209383 A209621 A209622
KEYWORD
nonn
AUTHOR
Robert Price, May 07 2012
EXTENSIONS
a(21)-a(36) from Andrew Howroyd, Dec 05 2015
STATUS
approved