%I A157543
%S A157543 1,3,66,1330,19815,310023,4512844,69146820,1023450345,13538157655,
%T A157543 163977086526,1870633964706,20447484311345,216134818489905,
%U A157543 2218284360150120,22111545640638832,213615563307370209
%N A157543 Half the number of length n integer sequences with sum zero and sum of 
               squares 242.
%H A157543 Ron Hardin, <a href="b157543.txt">Table of n, a(n) for n=2..50</a>
%F A157543 [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,0,242)/2.
%Y A157543 Sequence in context: A091470 A028567 A003359 this_sequence A157984 A157554 
               A165655
%Y A157543 Adjacent sequences: A157540 A157541 A157542 this_sequence A157544 A157545 
               A157546
%K A157543 nonn
%O A157543 2,2
%A A157543 Ron Hardin (rhhardin(AT)att.net) Mar 02 2009