57500460

Appears in sequences

• a(n) = (1/2)*(binomial(2n, n) - binomial(2n-2, n-1)).at n=13A024482
• 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) = 2. Also a(n) = sum of numbers in row n+1 of array T defined in A026009.at n=27A026010
• a(n) = binomial(2n-3,n-1) + binomial(2n-2,n-2).at n=14A097613
• Number of ways to select 15 knights from n knights sitting at a round table if no adjacent knights are chosen.at n=13A188225
• s(k)-s(j), where (k,j) is the least pair for which n divides s(k)-s(j), and s(j)=(1/2)C(2j,j).at n=42A205390