193930domain: NAppears in sequencesSum of the principal diagonals of a 2n X 2n square spiral.at n=33A137931Number of binary strings of length n with no substrings equal to 0000, 0010, or 0100.at n=21A164417Denominators of rationals with e.g.f. D(3,x), a Debye function.at n=40A227571