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A248437 Number of length 4+2 0..n arrays with every three consecutive terms having the sum of some two elements equal to twice the third.

%I A248437 #6 Jul 23 2025 11:42:03
%S A248437 2,9,28,101,198,327,462,691,932,1203,1474,1829,2184,2551,2954,3459,
%T A248437 3964,4501,5038,5653,6286,6925,7564,8327,9114,9907,10712,11577,12442,
%U A248437 13363,14284,15307,16342,17383,18454,19609,20764,21925,23098,24389,25680,27009
%N A248437 Number of length 4+2 0..n arrays with every three consecutive terms having the sum of some two elements equal to twice the third.
%C A248437 Row 4 of A248433
%H A248437 R. H. Hardin, <a href="/A248437/b248437.txt">Table of n, a(n) for n = 1..210</a>
%F A248437 Empirical: a(n) = -a(n-4) +a(n-5) +a(n-7) -a(n-8) +a(n-9) +a(n-11) -a(n-12) +a(n-13) +a(n-15) -a(n-21) -a(n-23) +a(n-24) -a(n-25) -a(n-27) +a(n-28) -a(n-29) -a(n-31) +a(n-32) +a(n-36)
%e A248437 Some solutions for n=6
%e A248437 ..4....1....3....1....5....3....2....6....5....4....3....2....5....3....5....1
%e A248437 ..5....5....4....3....3....1....4....2....4....2....5....1....4....3....1....3
%e A248437 ..6....3....2....2....1....2....0....4....6....0....1....3....6....3....3....5
%e A248437 ..4....4....3....1....2....0....2....0....2....4....3....2....2....3....5....1
%e A248437 ..2....2....1....0....3....4....1....2....4....2....2....4....4....3....4....3
%e A248437 ..0....3....5....2....4....2....3....4....0....3....4....3....6....3....6....5
%K A248437 nonn
%O A248437 1,1
%A A248437 _R. H. Hardin_, Oct 06 2014