A116227 n times n+4 gives the concatenation of two numbers m and m-9.
44, 53, 949949, 979652, 7771781677, 7900890078, 9920892098, 9949999499, 38773083432315, 41534158410840, 47433813119406, 52566186880591, 58465841589157, 61226916567682, 72258945037433, 86156896546723
Offset: 1