

A198297


Minimum number of clues needed to uniquely solve an n^2 X n^2 sudoku.


1




OFFSET

0,3


COMMENTS

McGuire, Tugemann, & Civario find a(3) = 17.


LINKS

Table of n, a(n) for n=0..3.
Gary McGuire, Bastian Tugemann, and Gilles Civario, There is no 16clue sudoku: solving the sudoku minimum number of clues problem (2012)
James Grime and Brady Haran, 17 and sudoku clues, Numberphile video (2012)


EXAMPLE

Every 4x4 board with 3 filled squares either cannot be completed, or can be completed in two or more ways. But with 4 filled squares it is possible:
+++
 12 
  
+++
 1 
  3
+++
Thus a(2) = 4.


CROSSREFS

Cf. A107739.
Sequence in context: A300315 A296628 A123234 * A317094 A116573 A195881
Adjacent sequences: A198294 A198295 A198296 * A198298 A198299 A198300


KEYWORD

nonn,hard,bref


AUTHOR

Charles R Greathouse IV, Jan 26 2012


STATUS

approved



