A116240 n times n+9 gives the concatenation of two numbers m and m-8.
93, 454, 538, 993, 7664, 9993, 72720, 99993, 356428, 643564, 999993, 9090909, 9999993, 35294117, 64705875, 99999993, 335664328, 664335664, 684210519, 818181818, 838056673, 846153846, 866028701, 980125138, 999999993
Offset: 1