47138domain: NAppears in sequencesNumbers k such that the k-th triangular number contains only digits {0,1,9}.at n=18A119048O.g.f.: A(x) = Sum_{n>=0} x^n*Product_{k=0..n} (1 + k*x).at n=12A124380Row lengths of irregular triangle A381587.at n=25A381357