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Post by GGoodie on Apr 7, 2011 20:40:04 GMT
5! - PRIME!!!!!11!111!1!!11one1!
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Post by Fringe Pioneer on Apr 8, 2011 11:01:42 GMT
112
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Post by GGoodie on Apr 8, 2011 21:05:55 GMT
+1
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Post by Fringe Pioneer on Apr 9, 2011 20:22:03 GMT
(n + 1) * 10n + 2 + (n + 2) * 10n + 1 + (n + 3) * 10n ...when n = 0.
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Post by Qwerty on Apr 9, 2011 21:06:12 GMT
124. Also, is there an inverse to the factorial function?
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Post by Fringe Pioneer on Apr 10, 2011 4:51:54 GMT
If there is, it's likely ((n - 1)!)-1, but I don't think there is a given operator for that function. I guess you could just use the question mark, unless it is reserved for some other operation.
53
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Post by Anonymousperson5 on Apr 10, 2011 5:59:51 GMT
I dunno the inverse factorial. I've always wished there was one.
2*32*7
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Post by Fringe Pioneer on Apr 10, 2011 15:02:46 GMT
127 is prime...
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Post by Anonymousperson5 on Apr 10, 2011 15:15:55 GMT
Aha! I remember doing another large power of two previously.
Two two two two two two twos.
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Post by Fringe Pioneer on Apr 10, 2011 19:55:58 GMT
3 * 43
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Post by Anonymousperson5 on Apr 11, 2011 2:11:54 GMT
Ten thirteens.
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Post by Fringe Pioneer on Apr 11, 2011 3:04:41 GMT
131 is prime...
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Post by Anonymousperson5 on Apr 11, 2011 3:06:14 GMT
Two two three elevens
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Post by Fringe Pioneer on Apr 11, 2011 3:07:34 GMT
7 * 19
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Post by Anonymousperson5 on Apr 11, 2011 3:14:12 GMT
2*67
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Post by Fringe Pioneer on Apr 11, 2011 3:15:56 GMT
33 * 5
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Post by Anonymousperson5 on Apr 11, 2011 3:17:04 GMT
23*17
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Post by Fringe Pioneer on Apr 11, 2011 3:27:02 GMT
137 is prime...
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Post by Elmach on Apr 11, 2011 5:38:19 GMT
138 is not. Because it is 2*3*23
As for the inverse factorial function...
Γ-1(n!)-1=n
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Post by Qwerty on Apr 11, 2011 13:35:29 GMT
20's not prime.
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Post by Fringe Pioneer on Apr 11, 2011 13:57:13 GMT
22 * 5 * 7
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Post by Anonymousperson5 on Apr 11, 2011 22:37:43 GMT
@qwerty Wha???
3*47
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Post by Elmach on Apr 12, 2011 1:32:15 GMT
2*71 can't be prime.
QWERTY, FIX YOUR POST OR ELSE.
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Post by Anonymousperson5 on Apr 12, 2011 3:01:38 GMT
DVORAK, FIX YOUR POST AT ONCE.
11*13
Yay for two-digit primes!
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Post by Fringe Pioneer on Apr 12, 2011 3:20:44 GMT
122
(n - 0)(n + 0) = n2
(n - 1)(n + 1) = n2 - 1
Therefore, the number one less than a square will always have factors (not necessarily prime) one above and one below the square root of the square...
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Post by Anonymousperson5 on Apr 12, 2011 3:41:38 GMT
Wait, doesn't that prove that any number one less than a square is composite? And four less, and nine less, etc.?
5*29
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Post by Elmach on Apr 12, 2011 3:42:09 GMT
Yes. And screw you for nonjaing.
122+2
Which is 73*2.
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Post by Anonymousperson5 on Apr 12, 2011 13:37:26 GMT
3*72
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Post by Fringe Pioneer on Apr 12, 2011 20:56:32 GMT
Wait, doesn't that prove that any number one less than a square is composite? And four less, and nine less, etc.? Yes, it does seem that a number that appears a square amount before a square will always be composite, given that the square root of that distance isn't one less than the square root of the square in question. (n - a)(n + a) = n 2 - a 2(n - (n - 1))(n + (n - 1)) = (n - n + 1)(n + n - 1) = (1)(2n - 1) = 2n - 1 (n - (n - 1))(n + (n - 1)) = n 2 - (n 2 - 2n + 1) = 2n - 1 Even if a = n - 1, it seems 2n - 1 could still very well be composite. Take the square 400, for example: n = 20 in that case, so n - 1 would be 19. 2n - 1 would be 39, and that is obviously divisible by 3. In a way, it seems that squares are like anti-prime mines: a prime can't be found trailing certain distances behind a square... 2 2 * 37
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Post by Anonymousperson5 on Apr 13, 2011 23:16:41 GMT
One farty-nine.
Prime.
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