505019869254domain: NAppears in sequencesNumber of base 4 circular n-digit numbers with adjacent digits differing by 1 or less.at n=28A124697a(n) = ((sqrt(5) + 3)^n + (-sqrt(5) -1)^n + (-sqrt(5) + 3)^n + (sqrt(5) - 1)^n) / 2^n.at n=28A215500