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A248438 Number of length 5+2 0..n arrays with every three consecutive terms having the sum of some two elements equal to twice the third.

%I A248438 #6 Jul 23 2025 11:42:09
%S A248438 2,9,36,165,342,601,884,1381,1922,2533,3144,3957,4770,5613,6524,7697,
%T A248438 8870,10149,11428,12873,14362,15857,17352,19165,21026,22893,24804,
%U A248438 26841,28878,31061,33244,35697,38170,40649,43200,45977,48754,51537,54340,57421
%N A248438 Number of length 5+2 0..n arrays with every three consecutive terms having the sum of some two elements equal to twice the third.
%C A248438 Row 5 of A248433
%H A248438 R. H. Hardin, <a href="/A248438/b248438.txt">Table of n, a(n) for n = 1..210</a>
%F A248438 Empirical: a(n) = a(n-1) -a(n-2) -a(n-6) +2*a(n-7) -3*a(n-8) +3*a(n-9) -a(n-10) +2*a(n-13) -3*a(n-14) +4*a(n-15) -4*a(n-16) +3*a(n-17) -a(n-18) -a(n-20) +3*a(n-21) -4*a(n-22) +4*a(n-23) -3*a(n-24) +2*a(n-25) -a(n-28) +3*a(n-29) -3*a(n-30) +2*a(n-31) -a(n-33) +a(n-34) -a(n-36) +a(n-37) -2*a(n-39) +3*a(n-40) -3*a(n-41) +a(n-42) -2*a(n-45) +3*a(n-46) -4*a(n-47) +4*a(n-48) -3*a(n-49) +a(n-50) +a(n-52) -3*a(n-53) +4*a(n-54) -4*a(n-55) +3*a(n-56) -2*a(n-57) +a(n-60) -3*a(n-61) +3*a(n-62) -2*a(n-63) +a(n-64) +a(n-68) -a(n-69) +a(n-70)
%e A248438 Some solutions for n=6
%e A248438 ..0....0....1....2....2....6....5....6....3....6....6....6....6....0....3....2
%e A248438 ..2....4....1....1....2....2....1....2....2....4....4....4....4....2....5....3
%e A248438 ..1....2....1....0....2....4....3....4....4....5....2....2....2....1....4....4
%e A248438 ..3....0....1....2....2....3....5....3....6....3....0....3....3....3....3....5
%e A248438 ..5....1....1....4....2....5....1....5....5....4....1....4....1....5....2....6
%e A248438 ..1....2....1....3....2....4....3....1....4....2....2....2....2....4....4....4
%e A248438 ..3....3....1....5....2....3....5....3....3....0....0....3....0....6....0....2
%K A248438 nonn
%O A248438 1,1
%A A248438 _R. H. Hardin_, Oct 06 2014