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A268113
Number of legal positions in Go played on an n X n+1 grid (each group must have at least one liberty).
3
5, 489, 321689, 1840058693, 93332304864173, 41945191530093646965, 166931297609667912727898521, 5882748866432370655674372752123193, 1835738613899845421140262364853644706891109, 5072588588647327658457862518216696854885169490987149
OFFSET
1,1
COMMENTS
Upper bounded by 3^{n*(n+1)}.
LINKS
J. Tromp and G. Farnebäck, Combinatorics of Go, Lecture Notes in Computer Science, 4630, 84-99, 2007.
EXAMPLE
For n=1 the 5 legal 1x2 boards are .. X. O. .X .O
CROSSREFS
Almost-square version of A094777.
Sequence in context: A206502 A198249 A160363 * A308132 A352181 A152513
KEYWORD
nonn,hard
AUTHOR
John Tromp, Jan 26 2016
STATUS
approved