A158140 - OEIS

%I #4 Mar 31 2012 12:35:25

%S 1,4,9,22,33,67,92,156,214,318,408,597,729,990,1221,1586,1885,2423,

%T 2820,3512,4090,4958,5674,6857,7729,9150,10335,12052,13441,15627,

%U 17270,19830,21924,24894,27304,30963,33715,37876,41277,46022,49835,55489,59786,66132

%N Number of nondecreasing integer sequences of length 6 with sum zero and sum of absolute values 2n.

%C a(n) = A000041(n)^2 for n<=3

%C a(n) = A000041(n)^2 - cumulative A000712(2*n-1-length), 0 <= 2*n-1-length <= floor(n/2) [empirical].

%H R. H. Hardin, <a href="/A158140/b158140.txt">Table of n, a(n) for n=1..999</a>

%K nonn

%O 1,2

%A _R. H. Hardin_ Mar 13 2009