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A209383
Meandric numbers for a river crossing up to 8 parallel roads at n points.
18
1, 1, 2, 4, 10, 23, 63, 155, 448, 1151, 3450, 9137, 28134, 76236, 239712, 661374, 2115046, 5921549, 19203568, 54422726, 178585838, 511343777, 1694965469, 4896195579, 16371992897, 47656781437, 160578870274, 470571482142, 1596323368095, 4705798878362, 16059653893209
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 8 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: A370646 A208452 A208453 * A209621 A209622 A209626
KEYWORD
nonn,changed
AUTHOR
Robert Price, May 07 2012
EXTENSIONS
a(21)-a(36) from Andrew Howroyd, Dec 05 2015
STATUS
approved