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!)
A215784 Number of permutations of 0..floor((n*6-1)/2) on even squares of an n X 6 array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing. 1

%I

%S 1,2,12,29,189,458,2988,7241,47241,114482,746892,1809989,11808549,

%T 28616378,186696108,452432081,2951712081,7153064162,46667304972,

%U 113091730349,737821743309,1788008493098,11665145978028,28268860698521

%N Number of permutations of 0..floor((n*6-1)/2) on even squares of an n X 6 array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing.

%C Column 6 of A215788.

%H R. H. Hardin, <a href="/A215784/b215784.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 16*a(n-2) - 3*a(n-4).

%F Empirical g.f.: x*(1 + 3*x)*(1 - x - x^2) / (1 - 16*x^2 + 3*x^4). - _Colin Barker_, Jul 23 2018

%e Some solutions for n=4:

%e ..0..x..1..x..3..x....0..x..1..x..3..x....0..x..1..x..2..x....0..x..1..x..2..x

%e ..x..2..x..5..x..8....x..2..x..5..x..7....x..3..x..4..x..6....x..3..x..4..x..5

%e ..4..x..6..x..9..x....4..x..6..x..9..x....5..x..7..x..9..x....6..x..7..x..9..x

%e ..x..7..x.10..x.11....x..8..x.10..x.11....x..8..x.10..x.11....x..8..x.10..x.11

%Y Cf. A215788.

%K nonn

%O 1,2

%A _R. H. Hardin_, Aug 23 2012

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 January 26 04:04 EST 2022. Contains 350572 sequences. (Running on oeis4.)