n times n+6 gives the concatenation of two numbers m and m-8.

Terms

a(0) =7a(1) =9a(2) =97a(3) =99a(4) =425a(5) =570a(6) =724a(7) =843a(8) =997a(9) =999a(10) =7807a(11) =9997a(12) =9999a(13) =36362a(14) =63633a(15) =99997a(16) =99999a(17) =326731a(18) =673264a(19) =999997a(20) =999999a(21) =4545451a(22) =5454544a(23) =9999997a(24) =9999999a(25) =47058820a(26) =52941175a(27) =99999997a(28) =99999999a(29) =331983804