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A210567 Meandric numbers for a river crossing up to 18 parallel roads at n points. 18
1, 1, 2, 4, 10, 23, 63, 155, 448, 1152, 3452, 9158, 28178, 76539, 240370, 665129, 2123439, 5964691, 19302316, 54898416, 179696557 (list; graph; refs; listen; history; text; internal format)



Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 18 parallel East-West roads n times.

Sequence derived from list of solutions described in A206432.


Table of n, a(n) for n=0..20.


Cf. A005316 (sequence for one road; extensive references and links).

Cf. A076876 (sequence for two parallel roads).

Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).

Cf. A206432 (sequence for unlimited number of parallel roads).

Cf. A076875, A076906, A076907.

Sequence in context: A209707 A210344 A210478 * A210592 A206432 A124480

Adjacent sequences:  A210564 A210565 A210566 * A210568 A210569 A210570




Robert Price, May 07 2012



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Last modified December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)