24943689

Appears in sequences

• Triangular array read by rows: T(n,k) is the number of f:{1,2,...,n}->{1,2,...,n} with exactly 2k elements that have a preimage of even (possibly zero) cardinality; n>=0, 0<=k<=floor(n/2).at n=29A225942
• a(n) = 30240*n^5-25200*n^4+5040*n^3+7320*n^2-2638*n+1.at n=4A272128