## Tags » Sequences And Series

#### Log-Convexity of the Bell Numbers

A sequence is said to be log-convex if, for all , .

In this post I give a short, combinatorial-flavored proof that the Bell numbers… 338 more words

Combinatorics

#### How do you expand √(a+b)?

This is a question that was recently asked on Quora:

Is it possible to expand ?

it’s easy to expand
or

or some other but what about aka.

151 more words
Math On The Web

#### Algebra 2 - Sequences

Q: What is the tenth term of the sequence: 4, 12, 36, 108, …?

Explanation:  It’s a geometric sequence because each term is multiplied by 3 to get the next term. 62 more words

ACT Math

#### Summation with Factorials

Problem:
Show that
.

Description:
In sigma notation, we are trying to prove
. Below, we present the same proof with and without sigma notation. 101 more words

Sequences And Series