1362439domain: NAppears in sequencesa(n) = Sum(((k-1)/2)*k!*Stirling_2(n,k),k=1..n).at n=7A083411Matrix product of Stirling2-triangle A008277(n,k) and unsigned Lah-triangle |A008297(n,k)|.at n=29A088729Exponential Riordan array [1, 1/(2-e^x)-1].at n=38A256893