1305745domain: NAppears in sequencesCoefficients of 1/(1-2*x-7*x^2)^(1/2); also, a(n) is the central coefficient of (1+x+2*x^2)^n.at n=12A084601Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 0), (0, -1, 0), (0, 1, -1), (1, 0, 0), (1, 1, 1)}.at n=10A150841