OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
A. A. Dobrynin, I. Gutman, S. Klavzar, P. Zigert, Wiener Index of Hexagonal Systems , Acta Applicandae Mathematicae 72 (2002), pp. 247-294.
I. Gutman, S. Klavzar, M. Petkovsek, and P. Zigert, On Hosoya polynomials of benzenoid graphs, Comm. Math. Comp. Chem. (MATCH), 43, 2001, 49-66.
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n) = (2*n^4 + 28*n^3 + 154*n^2 - 169*n + 111)/3.
G.f.: x*(42 + 5*x - 19*x^2 - 49*x^3 + 37*x^4)/(1-x)^5. - Bruno Berselli, Jul 27 2011
MAPLE
a := proc (n) options operator, arrow; (2/3)*n^4+(28/3)*n^3+(154/3)*n^2-(169/3)*n+37 end proc: seq(a(n), n = 1 .. 35);
PROG
(Magma) [(2*n^4 + 28*n^3 + 154*n^2 - 169*n + 111)/3: n in [1..40]]; // Vincenzo Librandi, Jul 26 2011
(PARI) a(n)=(2*n^4+28*n^3+154*n^2-169*n)/3+37 \\ Charles R Greathouse IV, Jul 26 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jul 25 2011
STATUS
approved