Timeline for Back-To-Front Permutation Index
Current License: CC BY-SA 3.0
2 events
| when toggle format | what | by | license | comment | |
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| Mar 10, 2017 at 0:57 | comment | added | ETHproductions |
Oh, that's genius. My answer takes (n-1)*(n-1)! + (n-3)*(n-3)! + (n-5)*(n-5)! + ..., which is equivalent to (n! - (n-1)!) + ((n+2)! - (n-3)!) + ((n-4)! - (n-5)!) + ... which is what your answer does.
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| Mar 10, 2017 at 0:51 | history | answered | Neil | CC BY-SA 3.0 |