a(n) = (10n+1)*(10n+9).

Terms

a(0) =9a(1) =209a(2) =609a(3) =1209a(4) =2009a(5) =3009a(6) =4209a(7) =5609a(8) =7209a(9) =9009a(10) =11009a(11) =13209a(12) =15609a(13) =18209a(14) =21009a(15) =24009a(16) =27209a(17) =30609a(18) =34209a(19) =38009a(20) =42009a(21) =46209a(22) =50609a(23) =55209a(24) =60009a(25) =65009a(26) =70209a(27) =75609a(28) =81209a(29) =87009