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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A195591 Number of ways to place 3n nonattacking kings on a vertical cylinder 6 X 2n. 1
16, 90, 344, 1082, 3036, 7918, 19648, 47058, 109796, 251126, 565512, 1257754, 2769196, 6046014, 13107536, 28246370, 60555636, 129237382, 274727320, 581960106, 1228931516, 2587886030, 5435818464, 11391730162, 23823647236, 49727668758, 103616086568 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Vertical cylinder: a chessboard where it is supposed that the columns 1 and 6 are in contact (number of columns = 6, number of rows = 2n).

LINKS

Table of n, a(n) for n=1..27.

V. Kotesovec, Non-attacking chess pieces

FORMULA

Recurrence: a(n) = -4*a(n-4) + 12*a(n-3) - 13*a(n-2) + 6*a(n-1).

G.f.: (1+10*x+7*x^2)/((x-1)^2*(2*x-1)^2).

a(n) = (31*n - 65)*2^n + 18*n + 66.

CROSSREFS

Cf. A194645, A061594, A137432.

Sequence in context: A119771 A055920 A055856 * A240292 A050406 A047674

Adjacent sequences:  A195588 A195589 A195590 * A195592 A195593 A195594

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Sep 21 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 | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 15 19:24 EDT 2018. Contains 316237 sequences. (Running on oeis4.)