474533530

Appears in sequences

• Double subfactorials: a(n) = (-1)^floor(n/2) * n!! * Sum_{i=0..floor(n/2)} (-1)^i/(n-2*i)!!.at n=19A334578
• a(n) = (2*n-1)!! * Sum_{k=1..n} (-1)^(k-1)/(2*k-1)!!.at n=10A368794