Pentagonal pyramidal number
Encyclopedia : P : PE : PEN : Pentagonal pyramidal number
A pentagonal pyramidal number is a number equal to the sum of the first few pentagonal numbers. The first few are 1, 6, 18, 40, 75, 126, 196, 288, 405, 550, 726, 936, 1183, 1470, 1800, 2176, 2601, 3078, 3610, 4200, 4851, 5566, 6348, 7200, 8125, and 9126.
See also
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