A116235 n times n+4 gives the concatenation of two numbers m and m-8.
79, 8155, 9799, 467345, 532652, 997999, 76450587, 99979999, 7801738413, 8593817621, 9208120791, 9999799999, 346667333465, 401461854013, 598538145984, 653332666532, 945207479451, 999997999999, 48349470735058
Offset: 1