0

What is sum first n factorial ?

flag
2 
 tinyurl.com/273a2cz – J. M. Aug 31 2010 at 8:01
5 
 Generally, if you have a question like this and don't know how to approach it, you should find the first few values, and then put them into research.att.com/njas/sequences. This isn't a great substitute for thinking hard about the problem, but it is an easy road to an answer. – Eric Tressler Aug 31 2010 at 8:03
3 
 Facetious answer: it's the sum of the first n factorials... – Yemon Choi Aug 31 2010 at 8:19
From a computational point of view, it is perhaps useful to rewrite it as $(1(1+2(1+3(1+4(1+\dots (1+(n-1)(1+n)))))))))$ which shows that it can be evaluated using $n$ multiplications and additions (instead of the ${n\choose 2}$ multiplications necessary for the obvious evaluation). – Roland Bacher Aug 31 2010 at 9:03
2 
 Dear Arjit, you should try to show some motivation/sign that you've done your homework before asking such questions here. I might remind you to read the faq. – Gjergji Zaimi Aug 31 2010 at 11:40
show 3 more comments

closed as off topic by Gjergji Zaimi, Martin Brandenburg, Andrew Stacey, Franz Lemmermeyer, Victor Protsak Aug 31 2010 at 12:03

Browse other questions tagged or ask your own question.