20725

Appears in sequences

• Square array, read by antidiagonal: T(n,k) = n*T(n,k-1)+(-1)^k*T(n,floor(k/2)).at n=58A089141
• Number of two element anti-chains in Riordan trees on n edges (also called non-redundant trees, i.e., ordered trees where no vertex has out-degree equal to 1).at n=10A139263
• E.g.f. satisfies: A(x) = 1 + x*A(x)^2*exp(x*A(x)).at n=5A213644
• a(n) = 10^(prime(n)-1) mod prime(n)^2.at n=36A265012
• Number of length-4 0..n arrays with no adjacent pair x,x+1 repeated.at n=11A269657
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 654", based on the 5-celled von Neumann neighborhood.at n=40A273332
• x-value of the smallest solution to 2*x^2 - p*y^2 = (-1)^((p+1)/4), p = A002145(n).at n=34A306618