274758382274domain: NAppears in sequencesa(n) = 4*a(n-1) - a(n-2) with a(0) = 2, a(1) = 4.at n=20A003500Numerators of continued fraction convergents to sqrt(768).at n=19A042480a(n) = 14*a(n-1) - a(n-2); a(0) = 2, a(1) = 14.at n=10A067902Number of perfect matchings in the twisted graph (C_4 X C_n)_(1234).at n=19A220867