A295209 - OEIS

%I #6 Jun 22 2022 11:22:27

%S 1,7,27,147,916,4938,27208,152236,848992,4746938,26555583,148468255,

%T 830063597,4640855585,25946470239,145065530889,811058197498,

%U 4534601269690,25352811924120,141746752099136,792501412285360

%N Number of n X 4 0..1 arrays with each 1 horizontally or vertically adjacent to 2 or 3 1's.

%C Column 4 of A295213.

%H R. H. Hardin, <a href="/A295209/b295209.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 8*a(n-1) -17*a(n-2) +27*a(n-3) -66*a(n-4) +182*a(n-5) -188*a(n-6) -199*a(n-7) -22*a(n-8) +185*a(n-9) +385*a(n-10) +169*a(n-11) +49*a(n-12) +408*a(n-13) +516*a(n-14) -492*a(n-15) -1779*a(n-16) -408*a(n-17) +326*a(n-18) -331*a(n-19) +505*a(n-20) -310*a(n-21) +217*a(n-22) -111*a(n-23) +4*a(n-24) -16*a(n-25) +4*a(n-26) +4*a(n-27) -a(n-28).

%e Some solutions for n=7

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

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

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

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

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

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

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

%Y Cf. A295213.

%K nonn

%O 1,2

%A _R. H. Hardin_, Nov 17 2017