[seqfan] n-sphere constants

[John W. Nicholson]

The following is from "The Tau Manifesto" section 5:
"The generalization of a circle to arbitrary dimensions, called a hypersphere or an n-sphere." 
Later a see:
"We see from these formulas that the surface area and volume formulas define two families of constants, which we’ll call τ_n and σ_n" . My question is how to make a family of constants in the OEIS and add constants like A000796 or A019692?

John W. Nicholson