Comments on: Name this stupidly basic math function for me
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Comments on Ask MetaFilter post Name this stupidly basic math function for meSat, 28 Feb 2009 19:01:39 -0800Sat, 28 Feb 2009 19:01:39 -0800en-ushttp://blogs.law.harvard.edu/tech/rss60Question: Name this stupidly basic math function for me
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me
Basic Mathematical NameFilter: Name This Sequence <br /><br /> Is there a <b>name</b> for the mathematical function that means "The sum of N plus every number (n-1), from N to 0"?<br>
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For example function(5) = 5+4+3+2+1. Yes, the answer is 15, but what is the <i>function</i> called?<br>
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I'm looking for something like "the mathematical X of a number" or "the Y sequence" -- or perhaps "The Completely Basic Sequence Name that Everybody Who Paid Attention in Algebra Knows Off The Top Of Their Head" <br>
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I'm completely unable to Google this in a way that makes any sense, and yes, its driving me nuts. Please put me out of my misery.post:ask.metafilter.com,2009:site.115430Sat, 28 Feb 2009 18:56:30 -0800bhancemathfunctionsequenceBy: The Tensor
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656797
I am not a mathematician (and also not YOUR mathematician), but how about <a href="http://en.wikipedia.org/wiki/Triangular_number">Triangular number</a>?comment:ask.metafilter.com,2009:site.115430-1656797Sat, 28 Feb 2009 19:01:39 -0800The TensorBy: adipocere
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656798
I don't believe there is a name for this. There is an amusing story invoving <a href="http://www.mathnotes.com/aw_gauss.html">Karl Gauss</a>, though. You'd think it would be called a "Gauss Sum," but that goes into set theory, with which I am unfamiliar.comment:ask.metafilter.com,2009:site.115430-1656798Sat, 28 Feb 2009 19:01:48 -0800adipocereBy: dnesan
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656799
I always knew it as the sum of the first n integers. But I can't recall any fancy name for it though.comment:ask.metafilter.com,2009:site.115430-1656799Sat, 28 Feb 2009 19:02:18 -0800dnesanBy: adipocere
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656802
Bah, I must have missed that one. You'd think they'd name it after Gauss. What gives? Does he just have too much stuff named after him already and they don't want all the other mathematicians to be jealous?comment:ask.metafilter.com,2009:site.115430-1656802Sat, 28 Feb 2009 19:03:38 -0800adipocereBy: grouse
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656804
You probably mean the <a href="http://www.research.att.com/~njas/sequences/A000217">triangular numbers</a>.<br>
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The optimal search strategy for integer sequences is surely to calculate the first few values and search the <a href="http://www.research.att.com/~njas/sequences/">On-Line Encyclopedia of Integer Sequences</a>.comment:ask.metafilter.com,2009:site.115430-1656804Sat, 28 Feb 2009 19:04:00 -0800grouseBy: pullayup
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656807
Somebody asked <a href="http://answers.google.com/answers/threadview/id/708478.html">Google</a> a while back. Remember when you could do that?comment:ask.metafilter.com,2009:site.115430-1656807Sat, 28 Feb 2009 19:07:30 -0800pullayupBy: bhance
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656812
Sweet jesus thank you Tensor & Grouse for finding that. <br>
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And yes, I miss Google Answers.comment:ask.metafilter.com,2009:site.115430-1656812Sat, 28 Feb 2009 19:13:20 -0800bhanceBy: Anything
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656835
It's also an <a href="http://mathworld.wolfram.com/ArithmeticSeries.html">arithmetic series</a> from 1 to n with 1 added between terms. There are other arithmetic series, varying on the starting point and the difference between the successive terms in the sum; e.g. 5+8+11+14+17+20 is another arithmetic series.comment:ask.metafilter.com,2009:site.115430-1656835Sat, 28 Feb 2009 19:50:38 -0800AnythingBy: dfan
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656847
Anyone who has this kind of question in the future, the place to look first is <a href="http://www.research.att.com/~njas/sequences/">The On-Line Encyclopedia of Integer Sequences</a>!comment:ask.metafilter.com,2009:site.115430-1656847Sat, 28 Feb 2009 20:06:03 -0800dfanBy: weapons-grade pandemonium
http://ask.metafilter.com/115430/Name-this-stupidly-basic-math-function-for-me#1656914
<a href="http://mathworld.wolfram.com/ArithmeticSeries.html">Arithmetic Series</a>: <br>
n = n(n+1)/2 <br>
<em>This is the trick Gauss used as a schoolboy to solve the problem of summing the integers from 1 to 100 given as busy-work by his teacher. While his classmates toiled away doing the addition longhand, Gauss wrote a single number, the correct answer<br>
1/2(100)(1+100)=50·101=5050 <br>
</em>comment:ask.metafilter.com,2009:site.115430-1656914Sat, 28 Feb 2009 22:42:44 -0800weapons-grade pandemonium