login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A287498 Number of maximal independent vertex sets (and minimal vertex covers) in the n-web graph. 0
0, 4, 9, 12, 30, 55, 105, 212, 405, 794, 1551, 3015, 5889, 11477, 22374, 43636, 85068, 165871, 323418, 630582, 1229517, 2397289, 4674198, 9113711, 17769780, 34647305, 67554891, 131717661, 256821477, 500747300 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..30.

Eric Weisstein's World of Mathematics, Maximal Independent Vertex Set

Eric Weisstein's World of Mathematics, Minimal Vertex Cover

Eric Weisstein's World of Mathematics, Web Graph

Index entries for linear recurrences with constant coefficients, signature (0,2,3,1).

FORMULA

G.f.: x^2*(-4 - 9*x - 4*x^2)/(-1 + 2*x^2 + 3*x^3 + x^4).

a(n) = 2*a(n-2) + 3*a(n-3) + a(n-4).

MATHEMATICA

Table[RootSum[-1 - 3 # - 2 #^2 + #^4 &, #^n &], {n, 20}]

LinearRecurrence[{0, 2, 3, 1}, {0, 4, 9, 12}, 20]

CROSSREFS

Sequence in context: A179808 A083351 A055381 * A174911 A032820 A197615

Adjacent sequences:  A287495 A287496 A287497 * A287499 A287500 A287501

KEYWORD

nonn,easy

AUTHOR

Eric W. Weisstein, May 25 2017

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 6 15:17 EST 2021. Contains 349563 sequences. (Running on oeis4.)