620470080domain: NAppears in sequencesa(n) = Sum_{j=0..n} A047072(j, n-j).at n=32A047073a(n) = 4*C(2n,n) - 3*0^n.at n=15A146534a(n) = 4*(2*n)! / (n!)^2.at n=15A240530Number of permutations of length n such that numbers at odd positions are monotone and numbers at even positions are also monotone.at n=30A257546