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A137432 Number of ways to place n^2 nonattacking kings on a 2n X 2n cylindrical chessboard. 23
4, 32, 344, 4460, 66532, 1118398, 20984924, 437500380, 10105541204, 257860425672, 7241521734020, 222770819826574, 7466859257161488, 271156951835070930, 10609740515840572076, 444982726973034212924, 19911203110764903275188, 946564783226311159219150 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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)

FORMULA

Conjecture: limit of a(n+1)/(n*a(n)) as n->infinity is e.

CROSSREFS

Cf. A018807, A173033.

Sequence in context: A123309 A186391 A231446 * A177750 A224993 A051489

Adjacent sequences:  A137429 A137430 A137431 * A137433 A137434 A137435

KEYWORD

nonn,nice,hard

AUTHOR

Vaclav Kotesovec, Aug 31 2011

EXTENSIONS

a(11)-a(12) from Vaclav Kotesovec, Sep 08 2011

a(13)-a(27) from Alex V. Breger, Sep 10 2011

a(28)-a(31) from Alex V. Breger, Sep 12 2011

STATUS

approved

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Last modified August 21 19:52 EDT 2017. Contains 290906 sequences.