Template:Did you know nominations/Telephone number (mathematics)

Telephone number (mathematics)
Created/expanded by David Eppstein (talk). Nominated by Carabinieri (talk) at 21:40, 30 March 2012 (UTC)
 * ... that the number of ways to place n rooks on an n &times; n chessboard in such a way that no two rooks attack each other is a telephone number?


 * Thanks for the nom, but the hook is not quite accurate as stated. Without restriction, the number of placements is just a factorial; it needs diagonal symmetry to be a telephone number. How about:


 * ALT1 ... that the number of ways to place n diagonally-symmetric rooks on an n &times; n chessboard in such a way that no two rooks attack each other is a telephone number?
 * —David Eppstein (talk) 18:15, 2 April 2012 (UTC)
 * Sorry, I should've read the article more carefully.--Carabinieri (talk) 17:27, 3 April 2012 (UTC)


 * Symbol confirmed.svg DYK criteria met. Going with ALT1. Cwmhiraeth (talk) 05:58, 25 April 2012 (UTC)