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%I #10 Mar 31 2012 13:21:02
%S 4,8,9,12,13,17,18,21,22,26,27,30,31,35,39
%N Numbers having exactly one representation as sum of squares>1.
%C A078134(a(n))=1.
%C The sequence is finite with a(15)=39 as last term, since numbers m>39 can be represented as sums of squares>1 (even of squares of primes and even of squares of 2, 3 and 4 and even of squares of 2, 3 and 5) in at least two ways. Proof: if m=40+4k, k>=0, then m=(k+10)*2^2=(k+1)*2^2+4*3^2; if m=41+4k, then m=(k+8)*2^2+3^2=(k+4)*2^2+5^2; if m=42+4k, then m=(k+6)*2^2+2*3^2=(k+2)*2^2+3^2+5^2; if m=43+4k, then m=(k+4)*2^2+3*3^2=k*2^2+2*3^2+5^2. - _Hieronymus Fischer_, Nov 11 2007
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SquareNumber.html">Square Number</a>.
%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%Y Cf. A000290, A078137, A078135, A078130.
%Y Cf. A078134, A078139, A090677, A078137, A134754, A134755.
%K nonn,fini,full
%O 1,1
%A _Reinhard Zumkeller_, Nov 19 2002
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