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%I #7 Nov 30 2020 21:40:39
%S 0,1,4,17,62,255,1026,4363,18656,81446,357708,1584110,7042396,
%T 31429998,140626375,630640342,2833200433,12748771157,57445747751,
%U 259170739397,1170566884224,5292311737901,23949417255984,108470668735077,491664303153769,2230174016940385,10122784007130716
%N Total number of interior vertices in the multigraphs of all unoriented series-parallel networks with n edges.
%C See A339285 for additional details.
%F a(n) = Sum_{k=1..n-1} k*A339285(n,k).
%o (PARI) \\ See A339285 for VertexWeighted.
%o seq(n)={subst(deriv(VertexWeighted(n,x,y)), y, 1)}
%Y Cf. A339225, A339232, A339285.
%K nonn
%O 1,3
%A _Andrew Howroyd_, Nov 30 2020