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A182563
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Number of ways to place n non-attacking semi-knights on an n x n chessboard
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1
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1, 6, 70, 1289, 33864, 1148760, 47700972, 2344465830, 133055587660, 8559364525414, 615266768106190, 48861588247978827, 4247584874013608724, 401107335066453376830, 40880928693752664368224
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OFFSET
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1,2
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COMMENTS
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Semi-knight is a semi-leaper [1,2]. Moves of a semi-knight are allowed only in [2,1] and [-2,-1]. See also semi-bishops (A187235).
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LINKS
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Table of n, a(n) for n=1..15.
V. Kotesovec, Non-attacking chess pieces, 5ed, p.270
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FORMULA
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Asymptotic: a(n) ~ n^(2n)/n!*e^(-3/2)
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CROSSREFS
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Cf. A182562, A201540, A201513, A002465, A201511, A197989, A201861
Sequence in context: A001448 A024489 A036361 * A211036 A050788 A027317
Adjacent sequences: A182560 A182561 A182562 * A182564 A182565 A182566
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KEYWORD
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nonn
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AUTHOR
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Vaclav Kotesovec, May 05 2012
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STATUS
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approved
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