A116256 Numbers k such that k*(k+6) gives the concatenation of two numbers m and m-5.
6, 96, 450, 545, 688, 853, 996, 4379, 5616, 9996, 72727, 99996, 346530, 653465, 999996, 9090905, 9999996, 94117643, 99999996, 334665330, 336032384, 378253325, 390977439, 439928488, 483516483, 516483512, 560071507
Offset: 1