A192850 Molecular topological indices of the web graphs.

46, 184, 414, 832, 1390, 2232, 3262, 4672, 6318, 8440, 10846, 13824, 17134, 21112, 25470, 30592, 36142, 42552, 49438, 57280, 65646, 75064, 85054, 96192, 107950, 120952, 134622, 149632, 165358, 182520

Offset

1,1

Comments

Web graphs are defined for n>=3; extended to n=1 using closed form.

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Molecular Topological Index

Index entries for linear recurrences with constant coefficients, signature (2,1,-4,1,2,-1).

Formula

a(n) = n*(6*n^2+22*n+3*((-1)^n+7)).

G.f.: 2*x*(x^4+2*x^3+46*x+23)/((x-1)^4*(x+1)^2). - Colin Barker, Aug 07 2012

E.g.f.: x*((49 +40*x +6*x^2)*exp(x) - 3*exp(-x)). - G. C. Greubel, Jan 05 2018

Mathematica

Table[n*(6*n^2+22*n+3*((-1)^n+7)), {n, 1, 40}] (* G. C. Greubel, Jan 05 2019 *)

Prog

(PARI) vector(40, n, n*(6*n^2+22*n+3*((-1)^n+7))) \\ G. C. Greubel, Jan 05 2019
(Magma) [n*(6*n^2+22*n+3*((-1)^n+7)): n in [1..40]]; // G. C. Greubel, Jan 05 2019
(Sage) [n*(6*n^2+22*n+3*((-1)^n+7)) for n in (1..40)] # G. C. Greubel, Jan 05 2019
(GAP) List([1..40], n -> n*(6*n^2+22*n+3*((-1)^n+7))); # G. C. Greubel, Jan 05 2019

Crossrefs

Sequence in context: A251467 A251460 A235767 * A211334 A160334 A235550

Adjacent sequences: A192847 A192848 A192849 * A192851 A192852 A192853

Keyword

nonn,easy

Author

Eric W. Weisstein, Jul 11 2011

Status

approved