147552domain: NAppears in sequencesa(n) = Sum_{k=0..n} Stirling1(n,k)^2.at n=6A047796Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 1), (0, -1), (0, 1), (1, -1)}.at n=12A151434