cp's OEIS Frontend

A221939 Number of 3Xn arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, without move-in move-out straight through or left turns.

%I A221939 #6 Jul 23 2025 02:21:16
%S A221939 1,91,1599,36467,799632,17595404,387146025,8517616158,187399250327,
%T A221939 4123030670649,90712135220235,1995786856338823,43909951229853113,
%U A221939 966076992787974879,21254971544597958477,467637484141672483673
%N A221939 Number of 3Xn arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, without move-in move-out straight through or left turns.
%C A221939 Row 3 of A221937
%H A221939 R. H. Hardin, <a href="/A221939/b221939.txt">Table of n, a(n) for n = 1..98</a>
%F A221939 Empirical: a(n) = 6*a(n-1) +286*a(n-2) +1731*a(n-3) -3366*a(n-4) -58755*a(n-5) -73158*a(n-6) +744580*a(n-7) +1606773*a(n-8) -5847271*a(n-9) -13299665*a(n-10) +35585397*a(n-11) +56858689*a(n-12) -168213873*a(n-13) -99886051*a(n-14) +532060381*a(n-15) -127805646*a(n-16) -951724652*a(n-17) +874261131*a(n-18) +729065885*a(n-19) -1511277493*a(n-20) +275583551*a(n-21) +992093720*a(n-22) -708567632*a(n-23) -119679569*a(n-24) +310913349*a(n-25) -92576435*a(n-26) -25624476*a(n-27) +17876348*a(n-28) -1254086*a(n-29) -1085212*a(n-30) +391330*a(n-31) -46391*a(n-32) -25190*a(n-33) +7306*a(n-34) +873*a(n-35) -236*a(n-36) -12*a(n-37) for n>38
%e A221939 Some solutions for n=3
%e A221939 ..1..1..2....0..4..0....1..1..1....1..1..2....0..4..0....0..3..1....2..0..1
%e A221939 ..0..1..3....1..0..1....0..4..0....0..2..0....1..0..1....0..0..2....0..3..0
%e A221939 ..0..0..1....0..3..0....0..0..2....1..1..1....1..1..1....2..0..1....0..2..1
%K A221939 nonn
%O A221939 1,2
%A A221939 _R. H. Hardin_ Feb 01 2013