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A137432
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Number of ways to place n^2 nonattacking kings on a 2n X 2n cylindrical chessboard.
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23
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4, 32, 344, 4460, 66532, 1118398, 20984924, 437500380, 10105541204, 257860425672, 7241521734020, 222770819826574, 7466859257161488, 271156951835070930, 10609740515840572076, 444982726973034212924, 19911203110764903275188, 946564783226311159219150
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Alex V. Breger, Table of n, a(n) for n = 1..31
V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights
Artem M. Karavaev, Zealint blog (in Russian)
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FORMULA
| Conjecture: limit of a(n+1)/(n*a(n)) as n->infinity is e.
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CROSSREFS
| Cf. A018807, A173033.
Sequence in context: A002005 A123309 A186391 * A177750 A051489 A047053
Adjacent sequences: A137429 A137430 A137431 * A137433 A137434 A137435
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KEYWORD
| nonn,hard
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AUTHOR
| Vaclav Kotesovec (kotesovec(AT)chello.cz), Aug 31 2011
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EXTENSIONS
| a(11)-a(12) from Vaclav Kotesovec, Sep 8 2011
a(13)-a(27) from Alex V. Breger, Sep 10 2011
a(28)-a(31) from Alex V. Breger, Sep 12 2011
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