300533760

Appears in sequences

• Number of reversible strings with n-1 black beads and n-1 white beads. String is not palindromic.at n=16A032095
• a(n) = (1/2)*(binomial(4*n, 2*n) - (-1)^n*binomial(2*n,n)).at n=8A037964
• Number of 2n-bead black-white complementable strings with n black beads and fundamental period 2n.at n=16A045630
• a(n) = Sum_{k=0..n} C(n,k)^2*mod(k,2).at n=16A110145
• Expansion of g(x) - x*g(x^2), where g(x) is the g.f. of A001405.at n=31A129383
• a(n) = Sum_{k=1..n, gcd(n,k) = 1} binomial(n,k)^2.at n=15A337003