484880domain: NAppears in sequencesa(n) = Product_{i=0..n-1} (9*i+2).at n=5A084949Nonuple factorial, 9-factorial, n!9, n!!!!!!!!!.at n=38A114806Square table read by downward antidiagonals: n-th row has e.g.f. (1-9*x)^(-n/9).at n=30A392037