cp's OEIS Frontend

A248428 Number of length n+2 0..3 arrays with every three consecutive terms having the sum of some two elements equal to twice the third.

%I A248428 #8 Nov 08 2018 06:34:18
%S A248428 16,20,24,28,36,44,52,68,84,100,132,164,196,260,324,388,516,644,772,
%T A248428 1028,1284,1540,2052,2564,3076,4100,5124,6148,8196,10244,12292,16388,
%U A248428 20484,24580,32772,40964,49156,65540,81924,98308,131076,163844,196612,262148
%N A248428 Number of length n+2 0..3 arrays with every three consecutive terms having the sum of some two elements equal to twice the third.
%H A248428 R. H. Hardin, <a href="/A248428/b248428.txt">Table of n, a(n) for n = 1..210</a>
%F A248428 Empirical: a(n) = a(n-1) + 2*a(n-3) - 2*a(n-4).
%F A248428 Empirical g.f.: 4*x*(4 + x + x^2 - 7*x^3) / ((1 - x)*(1 - 2*x^3)). - _Colin Barker_, Nov 08 2018
%e A248428 Some solutions for n=6:
%e A248428 ..1....1....1....2....2....0....1....1....2....3....2....1....1....0....0....3
%e A248428 ..0....3....2....1....0....1....0....3....0....2....0....3....1....1....0....1
%e A248428 ..2....2....3....3....1....2....2....2....1....1....1....2....1....2....0....2
%e A248428 ..1....1....1....2....2....3....1....1....2....3....2....1....1....0....0....0
%e A248428 ..0....0....2....1....0....1....3....0....0....2....3....3....1....1....0....1
%e A248428 ..2....2....3....0....1....2....2....2....1....1....1....2....1....2....0....2
%e A248428 ..1....1....1....2....2....3....1....1....2....0....2....1....1....3....0....3
%e A248428 ..0....0....2....1....3....1....3....3....0....2....3....0....1....1....0....1
%Y A248428 Column 3 of A248433.
%K A248428 nonn
%O A248428 1,1
%A A248428 _R. H. Hardin_, Oct 06 2014