8388521domain: NAppears in sequencesExpansion of (1-x)/(1-3x+x^2+4x^3-4x^4).at n=23A117353Start with a single square; at n-th generation add a square at each expandable vertex; a(n) is the sum of all label values at n-th generation. (See comment for construction rules.)at n=20A247618