140697113792domain: NAppears in sequencesa(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(n,2*k)^2.at n=23A307091Expansion of sqrt(2 / ( (1-12*x+4*x^2) * (1-2*x+sqrt(1-12*x+4*x^2)) )).at n=11A337370