login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A291375 Irregular triangle read by rows: number of  maximal irredundant sets of size k in the n-path graph. 2
0, 1, 0, 2, 0, 1, 1, 0, 0, 4, 0, 0, 5, 1, 0, 0, 2, 6, 0, 0, 0, 12, 1, 0, 0, 0, 8, 9, 0, 0, 0, 1, 25, 1, 0, 0, 0, 0, 28, 12, 0, 0, 0, 0, 12, 44, 1, 0, 0, 0, 0, 2, 68, 16, 0, 0, 0, 0, 0, 48, 73, 1, 0, 0, 0, 0, 0, 14, 150, 20, 0, 0, 0, 0, 0, 1, 155, 112, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

For each row, k lies in the range 0..ceiling(n/2). The upper end of the range is the upper irredundance number of the graph.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..990

Eric Weisstein's World of Mathematics, Maximal Irredundant Set

Eric Weisstein's World of Mathematics, Path Graph

FORMULA

T(n,k) = 0 for k < ceiling(n/3).

EXAMPLE

Triangle begins:

0, 1;

0, 2;

0, 1, 1;

0, 0, 4;

0, 0, 5,  1;

0, 0, 2,  6;

0, 0, 0, 12,  1;

0, 0, 0,  8,  9;

0, 0, 0,  1, 25,  1;

0, 0, 0,  0, 28, 12;

0, 0, 0,  0, 12, 44,  1;

0, 0, 0,  0,  2, 68, 16;

...

As polynomials these are: x; 2*x; x + x^2; 4*x^2; 5*x^2 + x^3; etc.

CROSSREFS

Row sums of A291055.

Sequence in context: A219023 A025427 A245963 * A033778 A091586 A116377

Adjacent sequences:  A291372 A291373 A291374 * A291376 A291377 A291378

KEYWORD

nonn,tabf

AUTHOR

Andrew Howroyd, Aug 23 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 June 26 04:11 EDT 2019. Contains 324369 sequences. (Running on oeis4.)