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A189851 Number of ways to place n nonattacking composite pieces rook + rider[1,4] on an n X n chessboard. 5
1, 2, 6, 24, 48, 182, 868, 5752, 22952, 131766, 912964, 7556978, 52602390, 432795244, 4121203656, 44335718598, 416447624724 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

In fairy chess, the rider [1,4] is called a Girafferider.

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+k)-p(i)|<>4k AND |p(j+4k)-p(j)|<>k for all i>=1, j>=1, k>=1, i+k<=n, j+4k<=n

LINKS

Table of n, a(n) for n=1..17.

V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)

Wikipedia, Fairy chess piece

CROSSREFS

Cf. A000170, A189837, A189850

Sequence in context: A092485 A113904 A099144 * A189563 A321613 A104114

Adjacent sequences:  A189848 A189849 A189850 * A189852 A189853 A189854

KEYWORD

nonn,hard

AUTHOR

Vaclav Kotesovec, Apr 29 2011

STATUS

approved

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Last modified February 19 09:57 EST 2020. Contains 332041 sequences. (Running on oeis4.)