Given 1, 1/2, 1/6, 1/24, 1/120

In this sequence the numerator of each term is 1. The terms in the denominator follow the n! (factorial) pattern. The expression for the nth them of the sequence is `a_n=1/(n!)`

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`a_1=1/(1!)=1`

` ` `a_2=1/(2!)=1/2`

`a_3=1/(3!)=1/6`

`a_4=1/(4!)=1/24`

`a_5=1/(5!)=1/120`