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A248460 Number of length n+2 0..7 arrays with no three consecutive terms having the sum of any two elements equal to twice the third.

%I A248460 #6 Jul 23 2025 11:43:53
%S A248460 432,2956,20236,138534,948412,6493036,44452660,304332258,2083523194,
%T A248460 14264241960,97656029050,668573914642,4577199017242,31336476646048,
%U A248460 214536174915418,1468760220688680,10055444434320028,68841708367472026
%N A248460 Number of length n+2 0..7 arrays with no three consecutive terms having the sum of any two elements equal to twice the third.
%C A248460 Column 7 of A248461
%H A248460 R. H. Hardin, <a href="/A248460/b248460.txt">Table of n, a(n) for n = 1..210</a>
%F A248460 Empirical: a(n) = 6*a(n-1) +9*a(n-2) -2*a(n-3) -109*a(n-4) -203*a(n-5) -4*a(n-6) +520*a(n-7) +1012*a(n-8) +696*a(n-9) +385*a(n-10) +373*a(n-11) -514*a(n-12) -2737*a(n-13) -4627*a(n-14) -3396*a(n-15) -2854*a(n-16) -3670*a(n-17) -2204*a(n-18) -634*a(n-19) -332*a(n-20) -162*a(n-21) -24*a(n-22)
%e A248460 Some solutions for n=4
%e A248460 ..0....4....7....2....1....2....0....6....1....7....0....4....1....4....0....0
%e A248460 ..4....5....0....4....4....5....0....5....4....2....1....5....0....7....2....1
%e A248460 ..4....2....7....5....0....6....3....5....1....0....4....2....7....3....7....5
%e A248460 ..3....4....4....4....5....1....2....6....4....2....3....2....1....1....6....1
%e A248460 ..7....7....3....0....6....5....6....0....1....2....7....7....5....0....6....2
%e A248460 ..1....0....6....5....0....7....5....2....6....3....6....1....0....1....1....7
%K A248460 nonn
%O A248460 1,1
%A A248460 _R. H. Hardin_, Oct 06 2014