The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A192845 Molecular topological indices of the sun graphs. 1
4, 56, 180, 400, 740, 1224, 1876, 2720, 3780, 5080, 6644, 8496, 10660, 13160, 16020, 19264, 22916, 27000, 31540, 36560, 42084, 48136, 54740, 61920, 69700, 78104, 87156, 96880, 107300, 118440 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Sun graphs are defined for n >= 3; extended to n=1 using closed form.
LINKS
Eric Weisstein's World of Mathematics, Molecular Topological Index
FORMULA
a(n) = 4*n*(-3 + 3*n + n^2).
a(n) = 4*A090197(n).
G.f.: 4*x*(1 + 10*x - 5*x^2)/(1-x)^4. - Colin Barker, Aug 07 2012
E.g.f.: 4*x*(1 + 6*x + x^2)*exp(x). - G. C. Greubel, Jan 05 2019
MATHEMATICA
Table[4*n*(-3+3*n+n^2), {n, 1, 40}] (* G. C. Greubel, Jan 05 2019 *)
LinearRecurrence[{4, -6, 4, -1}, {4, 56, 180, 400}, 30] (* Harvey P. Dale, Mar 02 2024 *)
PROG
(PARI) vector(40, n, 4*n*(-3+3*n+n^2)) \\ G. C. Greubel, Jan 05 2019
(Magma) [4*n*(-3+3*n+n^2): n in [1..40]]; // G. C. Greubel, Jan 05 2019
(Sage) [4*n*(-3+3*n+n^2) for n in (1..40)] # G. C. Greubel, Jan 05 2019
(GAP) List([1..40], n -> 4*n*(-3+3*n+n^2)); # G. C. Greubel, Jan 05 2019
CROSSREFS
Cf. A090197.
Sequence in context: A168133 A189864 A360262 * A144138 A331776 A006592
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jul 11 2011
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 22 04:07 EDT 2024. Contains 372742 sequences. (Running on oeis4.)