This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A173103 The number of possible borders of Latin squares with the top row fixed. 2
 1, 1, 2, 26, 924, 81624, 13433520, 3706068240, 1582042381920, 987057348842880, 861632512758823680, 1016677874552767660800, 1576819957670934809817600, 3140963381712726319842892800, 7880571655922780897709237811200, 24492587962448960350527019884595200 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS The definition is not quite right, and will be corrected soon. REFERENCES J. de Ruiter, On Jigsaw Sudoku Puzzles and Related Topics, Bachelor Thesis, Leiden Institute of Advanced Computer Science, 2010. - Johan de Ruiter, Jun 15 2010 LINKS Alois P. Heinz, Table of n, a(n) for n = 1..100 J. de Ruiter, On Jigsaw Sudoku Puzzles and Related Topics, Bachelor Thesis, Leiden Institute of Advanced Computer Science, 2010 FORMULA For n>3, a(n)=(n-2)!((n-1)/(n-2)d[n-1]^2+2d[n-1]d[n-2]+(2n-5)/(n-3)d[n-2]^2), where d[k] is the number of derangements of k elements (A000166). EXAMPLE The only two configurations for n=3, given the top row is 123: 123   123 2 1   3 2 312   231 Two arbitrary configurations for n=4, given the top row is 1234: 1234   1234 2  1   4  3 3  2   3  2 4123   2341 MAPLE d:= proc(n) d(n):= `if`(n<=1, 1-n, (n-1)*(d(n-1)+d(n-2))) end: a:= proc(n) a(n):= `if`(n<4, [1, 1, 2][n], (n-2)!*((n-1)/        (n-2)*d(n-1)^2+2*d(n-1)*d(n-2)+(2*n-5)/(n-3)*d(n-2)^2))     end: seq(a(n), n=1..20);  # Alois P. Heinz, Aug 18 2013 CROSSREFS Related to A000166. Equals A173104 divided by n!. Sequence in context: A059516 A210672 A290688 * A002704 A015215 A158120 Adjacent sequences:  A173100 A173101 A173102 * A173104 A173105 A173106 KEYWORD nonn AUTHOR Johan de Ruiter, Feb 09 2010 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.

Last modified October 23 22:15 EDT 2019. Contains 328373 sequences. (Running on oeis4.)