A pyramidal number of the form 
,
The first few are 1, 7, 22, 50, 95, ... (OEIS A002412).
The generating function of the hexagonal pyramidal
numbers is
 |
Hexagonal Pyramidal Number
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References
Sloane, N. J. A. Sequence A002412/M4374 in "The On-Line Encyclopedia of Integer Sequences."Referenced on Wolfram|Alpha
Hexagonal Pyramidal NumberCite this as:
Weisstein, Eric W. "Hexagonal Pyramidal Number." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/HexagonalPyramidalNumber.html