A209660 Meandric numbers for a river crossing up to 14 parallel roads at n points.

1, 1, 2, 4, 10, 23, 63, 155, 448, 1152, 3452, 9158, 28178, 76539, 240370, 665128, 2123437, 5964658, 19302248, 54897742, 179695133, 516457890, 1707112980, 4950547189, 16502992754, 48230509790, 161979310981, 476609746441, 1611226513378, 4769315213007, 16217954185533

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 14 parallel East-West roads n times.

Sequence derived from list of solutions described in A206432.

Links

Andrew Howroyd, Table of n, a(n) for n = 0..40

Crossrefs

Column k=14 of A380367.

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: A209626 A209656 A209657 * A209707 A210344 A210478

Adjacent sequences: A209657 A209658 A209659 * A209661 A209662 A209663

Keyword

nonn,changed

Author

Robert Price, May 07 2012

Extensions

a(21) onwards from Andrew Howroyd, Jan 31 2025

Status

approved