6327971

Appears in sequences

• Let t = coefficient of x^(2n+1) in expansion of sin(x)/(1-x^2); a(n)=denominator(t)-numerator(t).at n=5A067621
• Number of permutations of {1,2,...,n} having no up-down cycles. A cycle (b(1), b(2), ...) is said to be up-down if, when written with its smallest element in the first position, it satisfies b(1)<b(2)>b(3)<... .at n=11A186359
• a(n) = ((2*n+2)*(2*n+3) - 1)*a(n-1) + 2*n*(2*n+1)*a(n-2), a(0)=1, a(1)=19.at n=4A206308