ALLUDED TO BY FERMAT. 
641 
Diagkam No. 4. 
Natural numbers . 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
&c. 
Trigonal numbers . 
1 
3 
6 
10 
15 
21 
28 
36 
45 
55 
&c. 
Squares . . 
1 
4 
9 
16 
25 
36 
49 
64 
81 
100 
&c. 
Pentagonal . . . 
1 
5 
12 
22 
35 
51 
70 
92 
117 
145 
&c. 
Hexagonal . 
1 
6 
15 
28 
45 
66 
91 
120 
153 
190 
&c. 
Heptagonal . . . 
1 
7 
18 
34 
55 
81 
112 
148 
189 
! 
235 
&c. 
Octagonal , . 
1 
1 
8 
21 
40 
1 
65 
1 
96 
133 
176 
225 
280 
&c. 
