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%I #18 Jun 17 2022 14:29:01
%S 0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,
%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1
%N Number of Pythagorean triangles with area n.
%C The first term > 1 is a(210) = 2, cf. A009127, A055193 and A024407. Up to there the sequence coincides with the characteristic function of A009112. The triangles are not necessarily primitive.
%H Antti Karttunen, <a href="/A177063/b177063.txt">Table of n, a(n) for n = 1..65537</a>
%H <a href="/index/Ps#PyTrip">Index entries related to Pythagorean triples</a>.
%o (PARI) a(n)=my(N=1+#n=divisors(2*n));sum(i=1,N\2,issquare(n[i]^2+n[N-i]^2));
%Y Cf. A009111, A009127, A177021.
%K nonn
%O 1,210
%A _M. F. Hasler_, Dec 09 2010
%E Secondary offset added by _Antti Karttunen_, Nov 24 2017
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