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A210567
Meandric numbers for a river crossing up to 18 parallel roads at n points.
19
1, 1, 2, 4, 10, 23, 63, 155, 448, 1152, 3452, 9158, 28178, 76539, 240370, 665129, 2123439, 5964691, 19302316, 54898416, 179696557, 516468904, 1707136753, 4950705596, 16503341064, 48232611611, 161984008143, 476636172048, 1611286420859, 4769635283158, 16218689069176
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 18 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.
LINKS
CROSSREFS
Column k=18 of A380367.
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: A209707 A210344 A210478 * A210592 A206432 A124480
KEYWORD
nonn,changed
AUTHOR
Robert Price, May 07 2012
EXTENSIONS
a(21) onwards from Andrew Howroyd, Jan 31 2025
STATUS
approved