A192846 Molecular topological indices of the sunlet graphs.

14, 56, 126, 256, 430, 696, 1022, 1472, 1998, 2680, 3454, 4416, 5486, 6776, 8190, 9856, 11662, 13752, 15998, 18560, 21294, 24376, 27646, 31296, 35150, 39416, 43902, 48832, 53998, 59640

Offset

1,1

Comments

Sunlet 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

Eric Weisstein's World of Mathematics, Sun Graph

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

Formula

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

G.f.: 2*x*(x^4+2*x^3+14*x+7)/((x-1)^4*(x+1)^2). - Colin Barker, Aug 07 2012

E.g.f.: x*((15 + 12*x + 2*x^2)*exp(x) - exp(-x)). - G. C. Greubel, Jan 05 2019

Mathematica

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

Prog

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

Crossrefs

Sequence in context: A022285 A100157 A144555 * A212347 A115129 A281200

Adjacent sequences: A192843 A192844 A192845 * A192847 A192848 A192849

Keyword

nonn,easy

Author

Eric W. Weisstein, Jul 11 2011

Status

approved