cp's OEIS Frontend

A189327 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.

%I A189327 #7 Jul 22 2025 11:41:46
%S A189327 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 A189327 62,78,67,84,72,90,77,96,82,102,87,108,92,114,97,120,102,126,107,132,
%U A189327 112,138,117,144,122,150,127,156,132,162,137,168,142,174,147,180,152,186,157
%N A189327 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 A189327 Row 2 of A189326
%H A189327 R. H. Hardin, <a href="/A189327/b189327.txt">Table of n, a(n) for n = 1..200</a>
%F A189327 Empirical: a(n) = 2*a(n-2) -a(n-4)
%e A189327 All solutions for n=3
%e A189327 ..0....3....1....1....1....2....1
%e A189327 ..3....3....2....1....3....3....2
%e A189327 ..3....3....3....2....3....3....2
%e A189327 ..3....3....3....3....3....3....3
%K A189327 nonn
%O A189327 1,1
%A A189327 _R. H. Hardin_ Apr 20 2011