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%I #38 Sep 25 2018 14:21:53
%S 1,1,2,5,28,177,1982,33997,1020516,54570672,5347070228,967135763525,
%T 324200029119318,202046821340636691,234878262433630160622,
%U 511060736355598412146405,2088401066728281847415734793,16079824271822965645002329491423,233994776259866281916838227225733732
%N Number of connected balanced signed graphs on n unlabeled nodes.
%H Andrew Howroyd, <a href="/A318590/b318590.txt">Table of n, a(n) for n = 0..50</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Signed_graph">Signed graph</a>
%F a(2*n+1) = A054921(2*n+1)/2, a(2*n) = (a(n) + A054919(n) + A054921(2*n) - A054921(n))/2.
%F Inverse Euler transform of A034892.
%Y Cf. A005142, A034892, A053465, A054919, A054921.
%K nonn
%O 0,3
%A _Andrew Howroyd_, Sep 25 2018
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