cp's OEIS Frontend

A193391 Wiener index of a benzenoid consisting of a spiral chain of n hexagons (s=1; see the Gutman et al. reference).

%I A193391 #46 Sep 08 2022 08:45:58
%S A193391 27,109,271,529,899,1397,2039,2841,3819,4989,6367,7969,9811,11909,
%T A193391 14279,16937,19899,23181,26799,30769,35107,39829,44951,50489,56459,
%U A193391 62877,69759,77121,84979,93349,102247,111689,121691,132269,143439,155217,167619,180661
%N A193391 Wiener index of a benzenoid consisting of a spiral chain of n hexagons (s=1; see the Gutman et al. reference).
%H A193391 Vincenzo Librandi, <a href="/A193391/b193391.txt">Table of n, a(n) for n = 1..10000</a>
%H A193391 A. A. Dobrynin, I. Gutman, S. Klavzar, P. Zigert,<a href="http://www.fmf.uni-lj.si/~klavzar/preprints/Wiener-survey.pdf"> Wiener Index of Hexagonal Systems </a>, Acta Applicandae Mathematicae 72 (2002), pp. 247-294.
%H A193391 I. Gutman, S. Klavzar, M. Petkovsek, and P. Zigert, <a href="http://match.pmf.kg.ac.rs/electronic_versions/Match43/match43_49-66.pdf">On Hosoya polynomials of benzenoid graphs</a>, Comm. Math. Comp. Chem. (MATCH), 43, 2001, 49-66.
%H A193391 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F A193391 a(n) = (27 - 26*n + 72*n^2 + 8*n^3)/3.
%F A193391 G.f.: x*(27 + x - 3*x^2 - 9*x^3)/(1-x)^4. - _Bruno Berselli_, Jul 27 2011
%o A193391 (Magma) [(27 - 26*n + 72*n^2 +8*n^3)/3: n in [1..30]]; // _Vincenzo Librandi_, Jul 26 2011
%o A193391 (PARI) a(n)=(8*n^3+72*n^2-26*n)/3+9 \\ _Charles R Greathouse IV_, Jul 26 2011
%Y A193391 Cf. A143937, A143938, A193392.
%K A193391 nonn,easy
%O A193391 1,1
%A A193391 _Emeric Deutsch_, Jul 25 2011