1351616

Appears in sequences

• Number of reversible strings with n-1 black beads and n-1 white beads. String is not palindromic.at n=12A032095
• a(n) = (1/2)*(binomial(4*n, 2*n) - (-1)^n*binomial(2*n,n)).at n=6A037964
• a(n) = Sum_{k=0..n} C(n,k)^2*mod(k,2).at n=12A110145
• Expansion of g(x) - x*g(x^2), where g(x) is the g.f. of A001405.at n=23A129383