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Number of nondecreasing arrangements of 4 numbers in 0..n with the last equal to n and each after the second equal to the sum of one or two of the preceding four
2

%I #5 Mar 31 2012 12:36:15

%S 2,6,7,12,12,18,17,24,22,30,27,36,32,42,37,48,42,54,47,60,52,66,57,72,

%T 62,78,67,84,72,90,77,96,82,102,87,108,92,114,97,120,102,126,107,132,

%U 112,138,117,144,122,150,127,156,132,162,137,168,142,174,147,180,152,186,157

%N Number of nondecreasing arrangements of 4 numbers in 0..n with the last equal to n and each after the second equal to the sum of one or two of the preceding four

%C Row 2 of A189326

%H R. H. Hardin, <a href="/A189327/b189327.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 2*a(n-2) -a(n-4)

%e All solutions for n=3

%e ..0....3....1....1....1....2....1

%e ..3....3....2....1....3....3....2

%e ..3....3....3....2....3....3....2

%e ..3....3....3....3....3....3....3

%K nonn

%O 1,1

%A _R. H. Hardin_ Apr 20 2011