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%I #6 Jul 14 2013 05:22:34
%S 426,110582,1543242,12208658,76176642,419676194,2147525346,
%T 10478078306,49478563938,228185184866,1033790121570,4619196304994,
%U 20412418326114,89390811225698,388524258582114,1677932514369122,7207051830287970,30809448121032290,131162651106926178,556349805776789090,2352195514241310306
%N The Wiener index of the dendrimer D_4[n], defined pictorially in the A. R. Ashrafi et al. reference.
%C a(1) has been checked by the direct computation of the Wiener index (using Maple).
%D A. R. Ashrafi and H. Shabani, Computing Padmakar-Ivan index of four classes of dendrimers, Bulgarian Chem. Comm., 44, N0. 2, 2012, 127-130.
%F a(n) = -74142 + 2^n*(241658-45756*n)+4^n*(115320*n - 167090).
%F G.f.: 2*(213 +52522*z + 66470*z^2 -419644*z^3-33200*z^4)/((1-z)*(1-2*z)^2*(1-4*z)^2).
%p a := proc (n) options operator, arrow: -74142+2^n*(241658-45756*n)+4^n*(115320*n-167090) end proc: seq(a(n), n = 0 .. 20);
%Y Cf. A227485
%K nonn
%O 0,1
%A _Emeric Deutsch_, Jul 13 2013
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