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 17 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=17 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).
KEYWORD
nonn
AUTHOR
Robert Price, May 07 2012
EXTENSIONS
a(21) onwards from Andrew Howroyd, Jan 31 2025
STATUS
approved