|
|
A077055
|
|
Call two meanders from A005316 equivalent if they differ by a reflection in the Y axis (if n even) or by reflections in the X or Y axes (if n odd). Sequence gives number of inequivalent meanders with n crossings.
|
|
6
|
|
|
1, 1, 1, 2, 3, 8, 13, 42, 72, 273, 475, 1970, 3506, 15368, 27888, 126510, 233809, 1086546, 2039564, 9652364, 18360296, 88172609, 169610371, 824506191, 1601297937, 7865294687, 15401847339, 76331857094, 150547538649, 751981532942, 1492452957398
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,4
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
For n=7 the A005316(7) = 42 meanders with 7 crossings fall into 5 equivalence classes of size 2 and 8 of size 4, so a(7) = 5+8 = 13.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,nice
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|