8 May
2015
8 May
'15
9:16 a.m.
How are we defining 'arrangement'? This seems to be counting the number of tuples of distinct elements from an n-element set.
Sent: Friday, May 08, 2015 at 3:46 PM From: "Mike Speciner" <ms@alum.mit.edu> To: math-fun <math-fun@mailman.xmission.com> Subject: [math-fun] Sloane sequence A000522
This sequence is listed as Total number of arrangements of a set with n elements: a(n) = Sum_{k=0..n} n!/k!. But isn't the total number of arrangements of a set with n elements n! ? Isn't A000522 really the total number of arrangements of subsets of a set with n elements?
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