|
%I #12 Sep 05 2021 19:15:17
%S 1,3,9,20,49,115,343,850,2401,6698,18677,52383,148417,418280,1184717,
%T 3357537,9518235,27001128,76637532,217530615,617624137,1753811531,
%U 4980521844,14144892243,40174244540,114105904403,324101321331,920579535645,2614852152957
%N Number of tilings of a 4 X n rectangle using integer-sided rectangular tiles of equal area.
%C a(n+1)/a(n) tends to r = (1+sqrt(29)+sqrt(2*(7+sqrt(29))))/4 = 2.840536194094952533051131..., where r is the largest root of x^4-x^3-5*x^2-x+1. - _Vaclav Kotesovec_, Dec 21 2012
%H Alois P. Heinz, <a href="/A220770/b220770.txt">Table of n, a(n) for n = 0..1000</a>
%e a(2) = 9:
%e .___. .___. .___. .___. .___. .___. .___. .___. .___.
%e | | | | | | | |___| | | | |___| |___| | | | |_|_|
%e | | | | | |___| |___| |_|_| | | | |___| |_|_| |_|_|
%e | | | | | | | |___| |___| |_|_| | | | | | | |_|_|
%e |___| |_|_| |___| |___| |___| |___| |_|_| |_|_| |_|_|
%Y Column k=4 of A220777.
%K nonn
%O 0,2
%A _Alois P. Heinz_, Dec 19 2012
|
