A224601 - OEIS

%I #6 Aug 22 2016 05:15:23

%S 297,371,482,571,782,1086,1455,2010,2843,4018,5720,8226,11877,17199,

%T 24995,36409,53111,77574,113415,165921,242852,355585,520784,762873,

%U 1117653,1637589,2399570,3516286,5152892,7551432,11066640,16218405

%N Number of (n+2)X5 0..2 matrices with each 3X3 subblock idempotent

%C Column 3 of A224606

%H R. H. Hardin, <a href="/A224601/b224601.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) -6*a(n-2) +5*a(n-3) -4*a(n-4) +3*a(n-5) -a(n-6) for n>8.

%F Empirical g.f.: 297*x +371*x^2 -x^3*(-482+1357*x-1390*x^2+1026*x^3-876*x^4+366*x^5) / ( (x^3+x-1)*(x-1)^3 ). - _R. J. Mathar_, Aug 22 2016

%e Some solutions for n=3

%e ..0..1..0..0..0....1..0..0..0..0....1..0..0..0..0....1..0..0..0..0

%e ..0..1..0..0..0....1..0..0..0..0....1..0..0..0..0....1..0..0..0..0

%e ..0..1..0..0..0....1..0..0..0..0....1..0..0..0..0....1..0..0..0..0

%e ..0..1..0..0..0....0..0..0..0..0....0..0..0..0..1....0..0..0..0..0

%e ..0..0..0..0..1....2..0..0..1..1....0..0..0..0..1....0..2..1..1..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Apr 11 2013