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!)
A323499 Number of minimum dominating sets in the n-triangular (Johnson) graph. 1
1, 3, 15, 15, 195, 105, 2625, 945, 38745, 10395, 634095, 135135, 11486475, 2027025, 229053825, 34459425, 4996616625, 654729075, 118505962575, 13749310575, 3038597637075, 316234143225, 83802047954625, 7905853580625, 2474532170735625, 213458046676875 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 2..200

Eric Weisstein's World of Mathematics, Johnson Graph

Eric Weisstein's World of Mathematics, Minimum Dominating Set

Eric Weisstein's World of Mathematics, Triangular Graph

FORMULA

a(n) = n!! for n odd.

a(n) = (n-1)!!*(1 + n*(n/2 - 1)) for n even. - Andrew Howroyd, Sep 08 2019

PROG

(PARI) a(n)={my(m=(n+1)\2); ((2*m)!/(m!*2^m))*if(n%2, 1, 1 + n*(n/2-1))} \\ Andrew Howroyd, Sep 08 2019

CROSSREFS

Cf. A290716, A290847, A298104, A303048, A303227, A304561.

Sequence in context: A237628 A074043 A120467 * A332961 A012634 A043060

Adjacent sequences:  A323496 A323497 A323498 * A323500 A323501 A323502

KEYWORD

nonn

AUTHOR

Eric W. Weisstein, Jan 16 2019

EXTENSIONS

Terms a(14) and beyond from Andrew Howroyd, Sep 08 2019

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 July 2 21:48 EDT 2022. Contains 355029 sequences. (Running on oeis4.)