532 HISTORY OF THE THEORY OF NUMBERS. [CHAP, xix 



Then a solution of Euler's 164 problem is 



ax+(3y (3x-\-ay 2dt 2ay-\-yu+dt yt Su 



2(3y-yt-5u yu-dt (3x+ay ax+py 2yt 



(3x+ay-\-2dt ax (3y yt-\-du 2ay-}-yu 8t 



yu dt 2(3y+yt 8u ax+(3y+2yt fix ay, 



the sum of the squares of the numbers in any row, column or diagonal being 

 (<* 2 +/3 2 ) (z 2 +?/ 2 ) + (7 2 + 5 2 ) (t*+u 2 ) . 



Fuss 95 of Ch. V made p 2 +s 2 , g 2 +s 2 , r 2 +s 2 squares with pq+pr-\-qr = s 2 . 



PAPERS NOT AVAILABLE FOR REPORT. 



S. Giinther, Ziele u. Resultate d. neueren Math. Hist. Forschung, Erlangen, 1876, 50-53. 

 J. Favaro, Notize storico-critiche sulla costruzione delle equazioni, ModSne, 1878. 

 G. de Longchamps, Jour, de math. e!6m., 1882, 192; 28, 1894, 5. 

 Ferrent, ibid., (2), 3, 1884, 121, 155, 169, 193, 217, 241; 1885, 3, 170-1. 

 J. Novak, Ueber unbest. Gl. 2 Grades mit 2 Unbek., Progr. Budweis, 1890. 



