722 Figurate numbers
27.4 The polygonal numbersPn,k...............
More generally, for a fixedk, thek-gonal numbers are the sums of the
arithmetic progression
1+(k−1) + (2k−3) +···.
Thenthk-gonal number isPk,n=^12 n((k−2)n−(k−4)).
722 Figurate numbers
More generally, for a fixedk, thek-gonal numbers are the sums of the
arithmetic progression
1+(k−1) + (2k−3) +···.
Thenthk-gonal number isPk,n=^12 n((k−2)n−(k−4)).