34461586016domain: NAppears in sequencesNumber of reversible strings with n black beads and n-1 white beads. String is not palindromic.at n=19A032106a(n) = (1/4)*(binomial(4*n, 2*n) - (-1)^n*binomial(2*n, n) + (1-(-1)^n)*binomial(2*n, n)^2).at n=10A037976