324898

Appears in sequences

• Triangle read by rows: T(n,k) is the number of hill-free Schroeder paths of length 2n that have k returns to the x-axis (0<=k<=floor(n/2)). A Schroeder path of length 2n is a lattice path from (0,0) to (2n,0) consisting of U=(1,1), D=(1,-1) and H=(2,0) steps and never going below the x-axis. A hill is a peak at height 1.at n=31A114692
• Product of twin primes minus 1.at n=25A120875
• Number of 7-step one space for components leftwards or up, two space for components rightwards or down asymmetric quasi-bishop's tours (antidiagonal moves become knight moves) on an n X n board summed over all starting positions.at n=17A187611