Expansion of 1/((1-9x)(1-11x)).

Terms

a(0) =1a(1) =20a(2) =301a(3) =4040a(4) =51001a(5) =620060a(6) =7352101a(7) =85656080a(8) =985263601a(9) =11225320100a(10) =126965305501