19315400

Appears in sequences

• Expansion of 1/(1-4*x)^(13/2).at n=7A020924
• a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| = 1 for i = 1,2,...,n and s(0) = 3. Also a(n) = Sum{T(n,k), k = 0,1,...,[ (n+3)/2 ]}, where T is defined in A026022.at n=25A026023
• a(1) = 1. a(n) = n*a(n-1) if gcd(n,a(n-1)) = 1, a(n-1)/n if n divides a(n-1), otherwise a(n) = a(n-1).at n=24A068629
• a(n) = 2 * C(2*n,n-1).at n=13A162551
• Second column of the extended Catalan triangle A189231.at n=26A238452
• Convolution of the generalized Catalan numbers A057977 with themselves.at n=25A239453
• a(n) is the number of ballot sequences of length n tied or won by at most 3 votes.at n=25A337500