44781345

Appears in sequences

• Number of permutations in S_n avoiding the strings 123, 321 and 231.at n=18A060696
• Sum of product of odd numbers <= n and the product of even numbers <= n.at n=16A076051
• a(n) = (2n+1)!! + (2n)!! where k!! = A006882(k).at n=7A306185