I have to find the "second smallest root" of the following equation :

Matlab returns quite a satisfactory answer. >> p=[1/518400 -1/14400 1/1576 -1/36 1/4 -1 1]

p =

0.0000 -0.0001 0.0006 -0.0278 0.2500 -1.0000 1.0000

>> roots(p)

ans =

35.5690

-4.6796 +18.5352i

-4.6796 -18.5352i

4.1776 + 3.2154i

4.1776 - 3.2154i

1.4350

But I have been asked to identify this series as well, which I am unable to do. Can anybody help me identify this series as a function or a product of functions? Thanking anybody who answers before hand