Timeline for Is $\sum_{k=1}^{n}\frac{(n-1)!}{(k-1)!}$ composite for $n\geq 4$?
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
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| Oct 14, 2023 at 20:31 | answer | added | Conor Grogan | timeline score: 3 | |
| Jul 28, 2020 at 6:52 | vote | accept | solpa | ||
| Jul 27, 2020 at 18:38 | vote | accept | solpa | ||
| Jul 27, 2020 at 18:39 | |||||
| Jul 27, 2020 at 8:29 | comment | added | Alapan Das | The series $a_{n+1}=\sum_{k=0}^{n} \frac{n!}{k!}$ can be written in another representation. That is $$a_{n+1}=2^n+\sum_{k=2}^{n} \binom{n}{k}2^{n-k}D_k$$. Where, $D_k$ is the number of derangements. | |
| Jul 27, 2020 at 8:14 | comment | added | Ben Smith | $a_i$ is odd resp. even when $i$ is odd resp. even. So $a_i$ is certainly composite for all even $i$. | |
| Jul 27, 2020 at 7:28 | vote | accept | solpa | ||
| Jul 27, 2020 at 7:28 | |||||
| Jul 27, 2020 at 7:13 | answer | added | Fredrik Johansson | timeline score: 18 | |
| Jul 27, 2020 at 6:58 | comment | added | Fredrik Johansson | This is oeis.org/A000522 | |
| Jul 27, 2020 at 6:57 | history | edited | solpa | CC BY-SA 4.0 |
edited title
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| Jul 27, 2020 at 6:46 | history | edited | solpa | CC BY-SA 4.0 |
added 140 characters in body
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| Jul 27, 2020 at 6:26 | review | First posts | |||
| Jul 27, 2020 at 6:40 | |||||
| Jul 27, 2020 at 6:24 | history | asked | solpa | CC BY-SA 4.0 |