646296

Appears in sequences

• The (1,1)-entry in the 3 X 3 matrix M^n, where M = [1,2,1 / 2,2,0 / 1,0,0].at n=10A100191
• Expansion of g.f.: x^2*(1-2*x) / (1-3*x-3*x^2+2*x^3).at n=12A123950
• a(n) = n! * Sum_{k=1..n} ( Sum_{d|k} (-1)^(k/d+1) * d^2 )/(k * (n-k)!).at n=7A354508