A227488 - OEIS

%I #9 Nov 15 2016 03:02:36

%S 2192,75884,811076,5876276,35361428,191654996,973156820,4730314964,

%T 22295250644,102723642068,465158748884,2077879380692,9180871101140,

%U 40201652095700,174720788384468,754542896859860,3240816616917716

%N The Wiener index of the nanostar dendrimer NSC_5C_6[n], defined pictorially in the Ashrafi et al. and the Rostami et al. references.

%C a(2) has been checked by the direct computation of the Wiener index (using Maple).

%H A. R. Ashrafi and P. Nikzad, <a href="http://www.chalcogen.ro/1Ashrafi-Nikzad.pdf">Szeged index of nanostar dendrimers</a>, Digest J. of Nanomaterials and Biostructures, 4, No. 1, 2009, 155-157.

%H M. Rostami, M. Shabanian, and H. Moghanian, <a href="http://www.chalcogen.ro/247_Rostami.pdf">Some topological indices for theoretical study of two types of nanostar dendrimers</a>, Digest J. of Nanomaterials and Biostructures, 7, No. 1, 2012, 247-252.

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (13,-64,148,-160,64).

%F a(n) = -13612 + 2^n*(72*n + 45270) + 4^n*(12960*n - 31680).

%F G.f. = 4*z*(548 + 11847*z -8782*z^2 - 33888*z^3 - 352*z^4)/((1-z)*(1-2*z)^2*(1-4*z)^2).

%p a := proc (n) options operator, arrow: -13612+2^n*(72*n+45270)+4^n*(12960*n-31680) end proc: seq(a(n), n = 1 .. 20);

%Y Cf. A227489

%K nonn,easy

%O 1,1

%A _Emeric Deutsch_, Jul 16 2013