A209383 Meandric numbers for a river crossing up to 8 parallel roads at n points.

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

Andrew Howroyd, Table of n, a(n) for n = 0..36

Crossrefs

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: A370646 A208452 A208453 * A209621 A209622 A209626

Adjacent sequences: A209380 A209381 A209382 * A209384 A209385 A209386

Keyword

nonn

Author

Robert Price, May 07 2012

Extensions

a(21)-a(36) from Andrew Howroyd, Dec 05 2015

Status

approved