cp's OEIS Frontend

A252980 Number of n X 5 nonnegative integer arrays with upper left 0 and lower right its king-move distance away minus 2 and every value increasing by 0 or 1 with every step right, diagonally se or down.

%I A252980 #7 Mar 20 2018 10:17:07
%S A252980 6,41,266,1247,4657,67537,433401,1481460,3510600,6637020,10878576,
%T A252980 16235268,22707096,30294060,38996160,48813396,59745768,71793276,
%U A252980 84955920,99233700,114626616,131134668,148757856,167496180,187349640,208318236
%N A252980 Number of n X 5 nonnegative integer arrays with upper left 0 and lower right its king-move distance away minus 2 and every value increasing by 0 or 1 with every step right, diagonally se or down.
%C A252980 Column 5 of A252983.
%H A252980 R. H. Hardin, <a href="/A252980/b252980.txt">Table of n, a(n) for n = 1..210</a>
%F A252980 Empirical: a(n) = 557568*n^2 - 7467372*n + 25553940 for n>8.
%F A252980 Conjectures from _Colin Barker_, Mar 20 2018: (Start)
%F A252980 G.f.: x*(6 + 23*x + 161*x^2 + 566*x^3 + 1673*x^4 + 57041*x^5 + 243514*x^6 + 379211*x^7 + 298886*x^8 + 116199*x^9 + 17856*x^10) / (1 - x)^3.
%F A252980 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>11.
%F A252980 (End)
%e A252980 Some solutions for n=4:
%e A252980 ..0..0..1..1..2....0..0..0..0..1....0..0..0..0..0....0..1..1..1..1
%e A252980 ..0..0..1..1..2....1..1..1..1..1....0..1..1..1..1....0..1..1..1..1
%e A252980 ..1..1..1..1..2....1..1..1..1..2....1..1..1..2..2....0..1..1..1..1
%e A252980 ..1..1..1..1..2....1..2..2..2..2....1..1..2..2..2....0..1..2..2..2
%Y A252980 Cf. A252983.
%K A252980 nonn
%O A252980 1,1
%A A252980 _R. H. Hardin_, Dec 25 2014