Tag Archives: difference

An exploration of forward differences for bored elementary school students

Posted on March 22, 2020 by Brent

Last week I made a mathematics worksheet for my 8-year-old son, whose school is closed due to the coronavirus pandemic. I’m republishing it here so others can use it for similar purposes. Figurate numbers and forward differences There are lots … Continue reading →

Posted in arithmetic, teaching | Tagged coronavirus, difference, elementary, forward, homeschool, worksheet | 1 Comment

A combinatorial proof: PIE a la mode!

Posted on October 25, 2019 by Brent

Continuing from my last post in this series, we’re trying to show that , where is defined as which is what we get when we start with a sequence of consecutive th powers and repeatedly take successive differences. Recall that … Continue reading →

Posted in arithmetic, combinatorics, proof | Tagged consecutive, difference, function, integers, matching, powers | Comments Off

A combinatorial proof: counting bad functions

Posted on September 29, 2019 by Brent

In a previous post we derived the following expression: . We are trying to show that , in order to show that starting with a sequence of consecutive th powers and repeatedly taking successive differences will always result in . … Continue reading →

Posted in arithmetic, combinatorics, proof | Tagged consecutive, difference, function, integers, matching, powers | 1 Comment

A combinatorial proof: functions and matchings

Posted on September 26, 2019 by Brent

We’re trying to prove the following equality (see my previous post for a recap of the story so far): In particular we’re trying to show that the two sides of this equation correspond to two different ways to count the … Continue reading →

Posted in arithmetic, combinatorics, proof | Tagged consecutive, difference, function, integers, matching, powers | 5 Comments

A combinatorial proof: the story so far

Posted on September 6, 2019 by Brent

In my last post I reintroduced this seemingly odd phenomenon: Start with consecutive integers and raise them all to the th power. Then repeatedly take pairwise differences (i.e. subtract the first from the second, and the second from the third, … Continue reading →

Posted in arithmetic, combinatorics, proof | Tagged consecutive, difference, integers, powers | 1 Comment

A combinatorial proof: reboot!

Posted on August 31, 2019 by Brent

More than seven years ago I wrote about a curious phenomenon, which I found out about from Patrick Vennebush: if you start with a sequence of consecutive th powers, and repeatedly take pairwise differences, you always end up with , … Continue reading →

Posted in arithmetic, combinatorics, proof | Tagged consecutive, difference, integers, powers | 11 Comments

The Recamán sequence

Posted on June 12, 2016 by Brent

I recently learned about a really interesting sequence of integers, called the Recamán sequence (it’s sequence A005132 in the Online Encyclopedia of Integer Sequences). It is very simple to define, but the resulting complexity shows how powerful self-reference is (for … Continue reading →

Posted in arithmetic, recursion, sequences | Tagged difference, integers, Recamán, repeat, sequence | 5 Comments

Differences of powers of consecutive integers, part II

Posted on February 16, 2012 by Brent

If you spent some time playing around with the procedure from Differences of powers of consecutive integers (namely, raise consecutive integers to the th power, and repeatedly take pairwise differences until reaching a single number) you probably noticed the curious … Continue reading →

Posted in arithmetic, iteration, pascal's triangle | Tagged binomial coefficients, consecutive, difference, integers, powers | 3 Comments

Differences of powers of consecutive integers

Posted on January 29, 2012 by Brent

Patrick Vennebush of Math Jokes 4 Mathy Folks recently wrote about the following procedure that yields surprising results. Choose some positive integer . Now, starting with consecutive integers, raise each integer to the th power. Then take pairwise differences by … Continue reading →

Posted in arithmetic, pattern | Tagged consecutive, difference, integers, powers, surprising | 16 Comments