181215

Appears in sequences

• Number of permutations in S_n avoiding the strings 123, 321 and 231.at n=14A060696
• Sum of product of odd numbers <= n and the product of even numbers <= n.at n=12A076051
• Numerator of the coefficient of the n-th term of the power expansion near x = 0 of sqrt(1+1/sqrt(1-x))/sqrt(2).at n=5A295074
• a(n) = (2n+1)!! + (2n)!! where k!! = A006882(k).at n=5A306185