The Online Encyclopedia of Integer Sequences (OEIS) contains two distinct sequences involving 9-sided polygons:
- A060544: Centered 9-gonal numbers (also known as nonagonal or enneagonal numbers) These represent every third triangular number, starting with a(1)=1 https://oeis.org/A060544
- A195042: Concentric 9-gonal numbers https://oeis.org/A195042
What are the key geometric differences in how these two types of 9-gonal patterns are drawn or constructed? How does their visual representation differ?
