cp's OEIS Frontend

A189247 Number of n X 2 array permutations with each element making zero or one king moves.

%I A189247 #10 Jul 22 2025 11:37:35
%S A189247 2,24,152,1168,8448,62272,456320,3350016,24579584,180376576,
%T A189247 1323614208,9712930816,71274930176,523026923520,3838053810176,
%U A189247 28164247060480,206673697308672,1516604287614976,11129082140426240,81666965136998400
%N A189247 Number of n X 2 array permutations with each element making zero or one king moves.
%C A189247 Column 2 of A189254.
%H A189247 R. H. Hardin, <a href="/A189247/b189247.txt">Table of n, a(n) for n = 1..200</a>
%F A189247 Empirical: a(n) = 6*a(n-1) + 12*a(n-2) - 16*a(n-3).
%F A189247 Empirical g.f.: 2*x*(1 + 6*x - 8*x^2) / (1 - 6*x - 12*x^2 + 16*x^3). - _Colin Barker_, Mar 01 2018
%e A189247 Some solutions for 3 X 2:
%e A189247 ..1..2....1..2....1..2....3..1....0..1....1..0....0..2....2..0....2..1....0..1
%e A189247 ..0..3....0..4....3..0....5..0....4..2....3..2....3..1....5..1....3..0....3..5
%e A189247 ..5..4....5..3....4..5....4..2....3..5....5..4....4..5....4..3....4..5....2..4
%Y A189247 Cf. A189254.
%K A189247 nonn
%O A189247 1,1
%A A189247 _R. H. Hardin_, Apr 19 2011