520676

Appears in sequences

• 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=20A026010
• a(n) = binomial(2*n,n) - binomial(2*n-2,n-1); or (3n-2)*C(n-1), where C = Catalan numbers (A000108).at n=10A051924
• Expansion of (1+x)/(1-x)^12.at n=10A057788
• Triangle T(n,k), 0 <= k <= n, defined by : T(n,k) = 0 if k < 0, T(0,k) = 0^k, (n+2)*(2*n-2*k+1)*T(n,k) = (2*n+1)*( 4*(2*n-2*k+1)*T(n-1,k-1) + (n+2*k+2)*T(n-1,k) ).at n=39A123382
• s(k)-s(j), where (s(k),s(j)) is the least pair of central binomial coefficients for which n divides their difference.at n=30A205014
• a(n) is the number of ballot sequences of length n tied or won by at most 2 votes.at n=20A337499
• a(n) is the number of ballot sequences of length n tied or won by at most 3 votes.at n=20A337500