IIT JEE , AIEEE Forum - Mathematics , Algebra

umang_rathi777

_{solve this summation of n factorial}

_{[ 0]}

^{[n ]n!}

ankur.kkhurana

(n+1)!/n -1

fatafati

That's incorrect answer. Check by taking different values of n.

But nice attempt !!

sachin_batwani

Its (n+1)! - 1!

umang_rathi777

i am sorry but i also dont know answer

if any 1 gives answer plz justify it

konichiwa2x

The sum-of-factorials function is defined by

where

is the exponential integral.

is the En Function,

is the real part of

, and i is the imaginary number. The first few values are 1, 3, 9, 33, 153, 873, 5913, 46233, 409113, ...

but why do you need this? I am sure no problem of IIT level would require you to remember the above formula.

ankur.kkhurana

my answer may be wrong but method is correct
do you know about putting first and last value by breaking terms

well if you i can explain

iitkgp_bipin

konichiwa2x has already writen the expression for the sum of factorials.

If you want to gain knowedge on this topic you can refer to the link :

@ sachin_batwani, the summation of (r).(r!) gives (n+1)! - 1 and not of r!.

Best Wishes