Find the invalid no.from the following series 15, 17, 34, 105, 424, 2124, 12756
Choose the correct option:
A) 17  B) 34  C) 105  D) 424  E) 2124
2nd term = (1st term) * 1 + 1 = 15 *1 + 1= 
<gadget id="calculator">15 *1 + 1</gadget>
<output>16</output>
16.   3rd term= (2nd term) * 2 + 2 = 16 * 2 + 2= 
<gadget id="calculator">16 * 2 + 2</gadget>
<output>34</output>
34   4th term= (3th term) *3 + 3 = 34 * 3 + 3= 
<gadget id="calculator">34 * 3 + 3</gadget>
<output>105</output>
105   5th term= (4th term) * 4 + 4 = 105 * 4 + 4= 
<gadget id="calculator">105 * 4 + 4</gadget>
<output>424</output>
424   6th term= (5th term) * 5 + 5 = 424 * 5 + 5= 
<gadget id="calculator">424 * 5 + 5</gadget>
<output>2_125</output>
2125   2nd term should 16 instead of 17.   17
<result>A</result>
Find the invalid no.from the following series 15, 17, 34, 105, 424, 2124, 12756