8192524domain: NAppears in sequencesa(n) = Sum_{k=0..9} binomial(n,k).at n=27A008862Number of 1-punctured staircase polygons (by perimeter) with a hole of perimeter 4.at n=17A055022a(n) = Sum_{k=0..n} binomial(3*n,k).at n=9A066380