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A189283 Number of permutations p of 1,2,...,n satisfying p(i+4)-p(i)<>4 for all 1<=i<=n-4. 4

%I

%S 1,1,2,6,24,114,628,4062,30360,255186,2414292,25350954,292378968,

%T 3673917102,49928069188,729534877758,11403682481112,189862332575658,

%U 3354017704180052,62654508729565554,1233924707891272728,25550498290562247438

%N Number of permutations p of 1,2,...,n satisfying p(i+4)-p(i)<>4 for all 1<=i<=n-4.

%C a(n) is also number of ways to place n nonattacking pieces rook + semi-leaper[4,4] on an n X n chessboard.

%H Vaclav Kotesovec, <a href="/A189283/b189283.txt">Table of n, a(n) for n = 0..27</a> (Updated Jan 19 2019)

%H V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Number of ways of placing non-attacking queens, kings, bishops and knights</a> (in English and Czech)

%H Vaclav Kotesovec, <a href="/A189283/a189283.txt">Mathematica program for this sequence</a>

%F Asymptotic (V. Kotesovec, Mar 2011): a(n)/n! ~ (1 + 7/n + 12/n^2)/e.

%Y Cf. A000255, A189281, A189282, A189255.

%K nonn,hard

%O 0,3

%A _Vaclav Kotesovec_, Apr 19 2011

%E Terms a(26)-a(27) from _Vaclav Kotesovec_, Apr 20 2012

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Last modified August 3 02:14 EDT 2021. Contains 346430 sequences. (Running on oeis4.)