## Epic Systems Interview Question

Software Engineer / Developers**Country:**United States

**Interview Type:**Written Test

This is to determine sequence, a topic from discrete math.

We seek a_n, where

a_1 = -3 = -1 * 3

a_2 = 6 = 1 * 3 * 2

a_3 = -18 = -1 * 6 * 3

a_4 = 72 = 1 * 18 * 4

a_5 = -360 = -1 * 72 * 5

By inspection, the sequence is produced by

with initial condition n =1:

a_1 = -3

and subsequent sequence given by

a_n = (-1)**(n-1) * a_(n-1) * n for n > 2

Implemented in python:

{

import math

def a(n):

init = -3

pre = init

print pre

i = 2

while i < n + 1:

answer = (-1)**(i) * abs(pre) * i

print answer

pre = answer

i = i + 1

}

>>> a(6)

-3

6

-18

72

-360

2160

-3 x -2 = 6

- learner123 April 25, 20146 x -3 = -18

-18 x -4 = 72

72 x -5 = -360

-360 x -6 = 2160

so next number in the series is 2160.