%I
%S 4,8,9,12,13,16,17,18,20,21,22,24,26,27,28,30,31,32,35,39
%N Numbers having exactly one representation as sum of squares of primes.
%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%F A090677(a(n)) = 1.
%t Flatten[Position[Rest[CoefficientList[Series[Product[1/(1  x^(Prime[k]^2)), {k, 1, 5}], {x, 0, 40}], x]], 1]]
%Y Cf. A001248, A078135, A078136, A090677, A134755.
%K nonn,fini,full
%O 1,1
%A _Ilya Gutkovskiy_, Nov 02 2017
