Definition:Second Pentagonal Number

Definition
The second pentagonal numbers are those denumerating a collection of objects which can be arranged in the form of a regular pentagon.

They can be denoted:
 * $\map {P'} 1, \map {P'} 2, \map {P'} 3, \ldots$

Also see

 * Equivalence of Definitions of Second Pentagonal Number


 * Definition:Pentagonal Number
 * Definition:Generalized Pentagonal Number