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Half the number of length n integer sequences with sum zero and sum of squares 7200.
1

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

%S 1,3,126,23870,2725455,314174553,29749465207,2182715679324,

%T 150186806030400,10125676123572801,666260841650613825,

%U 42448715774998807794,2597948199840416316530,152089661374768398565935

%N Half the number of length n integer sequences with sum zero and sum of squares 7200.

%H R. H. Hardin, <a href="/A157592/b157592.txt">Table of n, a(n) for n=2..50</a>

%F [cache enabling] count(n,s,ss)->count(n,t,tt) where t=s mod n, q=(t-s)/n, tt=ss+2*q*s+n*q^2; count(n,t,tt)=sum[i^2<=tt]{ count(n-1,t-i,tt-i^2) }. a(n)=count(n,0,7200)/2.

%K nonn

%O 2,2

%A _R. H. Hardin_ Mar 02 2009