36810643323domain: NAppears in sequencesa(0) = 3, a(1) = 8, a(n+2) = 4*a(n+1) - a(n) - 2.at n=18A102206a(n) = ((sqrt(3)+1)^n+(sqrt(3)-1)^n)^2/2^(n+1).at n=19A121401Consider all consecutive integer Pythagorean septuples (X, X+1, X+2, X+3, Z-2, Z-1, Z) ordered by increasing Z; sequence gives Z values.at n=9A157089