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A224153 Number of n X 3 0..1 arrays with diagonals and rows unimodal and antidiagonals nondecreasing. 1

%I #8 Aug 28 2018 09:46:04

%S 7,28,89,281,900,2935,9681,32020,105937,350311,1157860,3826287,

%T 12643725,41780500,138063433,456233915,1507641652,4982061047,

%U 16463412165,54403960596,179779885769,594089193379,1963189403076,6487431018743

%N Number of n X 3 0..1 arrays with diagonals and rows unimodal and antidiagonals nondecreasing.

%C Column 3 of A224158.

%H R. H. Hardin, <a href="/A224153/b224153.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - a(n-3) - 4*a(n-4) + 14*a(n-5) - 2*a(n-6) - 2*a(n-9).

%F Empirical g.f.: x*(7 - 9*x^2 - 12*x^3 + 10*x^4 - 2*x^8) / (1 - 4*x + 2*x^2 + x^3 + 4*x^4 - 14*x^5 + 2*x^6 + 2*x^9). - _Colin Barker_, Aug 28 2018

%e Some solutions for n=3:

%e ..0..1..0....0..0..0....0..0..0....1..0..0....0..0..0....0..0..0....0..1..0

%e ..1..1..1....1..0..0....1..1..0....0..1..1....1..0..0....1..1..1....1..1..0

%e ..1..1..1....1..1..1....1..1..0....1..1..0....0..1..0....1..1..1....1..0..0

%Y Cf. A224158.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 31 2013

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Last modified March 19 01:34 EDT 2024. Contains 370952 sequences. (Running on oeis4.)