21580

Appears in sequences

• Triangle read by rows: T(n,k) is the number of binary trees with n edges and k jumps (n >= 0, 0 <= k <= max(0,ceiling(n/2)-1) ).at n=34A127530
• a(n) = 25*2^(n+3) - (198+392*n/3+36*n^2+10*n^3/3).at n=7A169833
• a(n) is the smallest integer k such that sigma_2(k) = sigma_2(k + 2n), where sigma_2(k) is the sum of squares of divisors of k (A001157).at n=19A175199
• Triangle read by rows: T(n,k) is the number of polygons formed by connecting the vertices of a regular 2n-gon such that the winding number around the center is k and with no side passing through the center.at n=10A343369