A235591 Numbers which on division by their digital root give quotient which is divisible by its digital root.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 18, 19, 20, 21, 24, 27, 28, 30, 36, 37, 38, 40, 42, 45, 46, 50, 54, 55, 56, 57, 60, 63, 64, 70, 72, 73, 74, 76, 80, 81, 82, 84, 90, 91, 92, 95, 100, 108, 109, 110, 111, 112, 114, 118, 120, 127, 128, 133, 136, 138, 140, 145, 146, 148, 152, 154, 162, 163, 164, 165, 168, 171, 172

Offset: 1

Author

Mihir Mathur, Jan 12 2014

Keywords

• nonn
• base
• easy

Examples

			 108 is a term as on division by its digital root i.e. 9, gives 12, which is again divisible by its digital root i.e. 3.
		

Programs

Mathematica

dr[n_] := 1 + Mod[n-1, 9]; Select[Range@172, IntegerQ[q = #/dr@#] && Mod[q, dr@q] == 0 &] (* Giovanni Resta, Jan 14 2014 *)