553246848000domain: NAppears in sequencesExpansion of e.g.f. 1/(1-2*x-x^2).at n=11A052555a(n) is the denominator of Sum_{k=1..n} 1 / (k*k!).at n=10A354401a(n) is the denominator of Sum_{k=1..n} (-1)^(k+1) / (k*k!).at n=10A354404