379501250domain: NAppears in sequencesa(n) = -(u^n-1)*(v^n-1) with u = 2+sqrt(3), v = 2-sqrt(3).at n=14A129743Continued fraction expansion for exp( Sum_{n>=1} 1/(n*A003500(n)) ), where A003500(n) = (2+sqrt(3))^n + (2-sqrt(3))^n.at n=29A174500Number of perfect matchings in the graph C_4 X C_n.at n=12A220864