A146123 - OEIS

%I #12 Mar 23 2018 12:28:33

%S 1,540,4120,12188,31000,67216,129464,228136,375388,585140,873076,

%T 1256644,1755056,2389288,3182080,4157936,5343124,6765676,8455388,

%U 10443820,12764296,15451904

%N Number of n X n arrays of squares of integers with every (n-3) X (n-3) subblock summing to 4 and every element equal to at least one neighbor.

%F Empirical (for n>=8): 147*n^4/2 - 1355*n^3 + 18985*n^2/2 - 29703*n + 34996. - _Vaclav Kotesovec_, Nov 30 2012

%F Conjectures from _Colin Barker_, Mar 23 2018: (Start)

%F G.f.: x^5*(1 + 535*x + 1430*x^2 - 3022*x^3 + 5865*x^4 - 4405*x^5 + 1564*x^6 - 204*x^7) / (1 - x)^5.

%F a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>12.

%F (End)

%K nonn

%O 5,2

%A _R. H. Hardin_, Apr 14 2009