cp's OEIS Frontend

A202974 Number of n X 3 0..1 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors.

%I A202974 #12 Jun 04 2018 04:29:27
%S A202974 1,4,17,58,215,866,3507,14120,56921,229860,928443,3749720,15144167,
%T A202974 61165438,247041429,997775144,4029911351,16276407572,65738788527,
%U A202974 265512410122,1072378133103,4331228325504,17493399301365,70654095337584
%N A202974 Number of n X 3 0..1 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors.
%C A202974 Column 3 of A202979.
%H A202974 R. H. Hardin, <a href="/A202974/b202974.txt">Table of n, a(n) for n = 1..210</a>
%F A202974 Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 16*a(n-3) - 14*a(n-4) - 3*a(n-5) + 8*a(n-6) - 9*a(n-7) - 2*a(n-8) + 6*a(n-9) + 2*a(n-10).
%F A202974 Empirical g.f.: x*(1 - 2*x + 4*x^2 - 16*x^3 + 4*x^4 + x^5 - 10*x^6 + 4*x^7 + 8*x^8 + 2*x^9) / (1 - 6*x + 11*x^2 - 16*x^3 + 14*x^4 + 3*x^5 - 8*x^6 + 9*x^7 + 2*x^8 - 6*x^9 - 2*x^10). - _Colin Barker_, Jun 03 2018
%e A202974 Some solutions for n=5:
%e A202974   1 1 1    0 1 1    1 1 1    0 1 1    0 0 0    1 1 1    1 1 0
%e A202974   1 1 1    1 1 1    1 1 1    1 1 1    0 1 1    1 0 1    1 1 1
%e A202974   0 0 0    1 1 1    1 0 0    1 0 1    1 1 1    1 0 1    1 0 1
%e A202974   0 0 0    1 1 0    1 1 1    1 1 1    1 1 1    1 0 1    1 1 1
%e A202974   0 0 0    0 0 0    1 1 1    0 1 1    0 1 1    1 1 1    0 0 0
%Y A202974 Cf. A202979.
%K A202974 nonn
%O A202974 1,2
%A A202974 _R. H. Hardin_, Dec 26 2011