Engler — Figurate Numbers. 



49 



For the sum of (d) we have by (4) 



n (n + 1) (n + 2) (n+'S) jn-l) n (?i + l) (n + 2) 



1-2-3 



For d = 3, these series become 

 12 2 2 2 

 113 5 7 

 1 3 8 15 

 112 10 25 



1-2-3-4 



(IJ) 



For f/ = 2, 



For f/=l, 



For f/ = 0. 



Table 16. 

 which is identical with Table 6. 



11111 

 12 3 4 5 

 1 3 6 10 15 

 1 4 10 20 35 



Table 17. 

 which is identical with Table 6 and Table 16. 



