For example, is a Jordan-Polya number, because it can be written as .
Jordan-Polya numbers arise in the following simple combinatorial problem. If groups of distinct objects are given, then the number of distinct permutations of the objects which maintain objects of the same group adjacent are , a Jordan-Polya number.
The first Jordan-Polya numbers are 1, 2, 4, 6, 8, 12, 16, 24, 32, 36, 48, 64, 72, 96, 120, 128, 144, 192, 216, 240, 256, 288, 384, 432, 480, 512, 576, 720, 768, 864, 960, 1024, 1152, 1296, 1440, 1536, 1728, 1920 more terms