143735627861domain: NAppears in sequencesExpansion of (1-3*x+x^2)^2/(1-9*x+28*x^2-35*x^3+15*x^4-x^5).at n=20A216710Number of (n+4) X 1 arrays of occupancy after each element moves up to +-4 places including 0.at n=16A222341