-11781domain: ZAppears in sequencesList of quadruples (r,s,t,u): the matrix M = [[4,12,9][2,5,3][1,2,1]] is raised to successive negative powers, then (r,s,t,u) are the square roots of M[1,3], M[1,1], M[3,3], M[3,1] respectively.at n=28A249580Triangle read by rows: Riordan array (1/(1-9x)^(2/3), x/(9x-1)).at n=24A283151