I little help?

[toonski84]

low budget canadian movies should only be watched in the backdrop of an mst3k episode...

[whitetiger0990]

nope... It finds prime numbers

If I'm reading that correctly, it looks like 35 is a prime. Reminds me of the Cube *shudders at the awfulness of low budget canadian films*

Well it is sometimes both sub. and add. Sometimes not.

[Agamemnus]

See Challenges post regarding impossibility of prime number equation.

[toonski84]

It's a nice little trick, like 7/22 for pi, but it skips over numbers, and after awhile will start producing non-primes. This table has primes on the left, and 6x+1 and 6x-1 on the other side.

Code:

3             1            -1
5             7             5
7             13            11
11            19            17
13            25            23
17            31            29
19            37            35
23            43            41
29            49            47
31            55            53
37            61            59
41            67            65
43            73            71
47            79            77
53            85            83
59            91            89
61            97            95
67            103           101
71            109           107
73            115           113
79            121           119
83            127           125
89            133           131

[Glenn]

produce prime numbers sometimes but not always.

[relsoft]

I guess I'll stick it out with Erathosthenes' Seive. :*)

[whitetiger0990]

I use it like this -

Code:

CLS
INPUT n
FOR i = 1 TO n
a = i * 6 - 1
b = i * 6 + 1
IF a <= n THEN
z = 1
DO
  z = z + 1
  IF z = a THEN PRINT a: EXIT DO
  IF a / z = INT(a / z) THEN EXIT DO
LOOP
END IF
IF b <= n THEN
z = 1
DO
  z = z + 1
  IF z = b THEN PRINT b: EXIT DO
  IF b / z = INT(b / z) THEN EXIT DO
LOOP
END IF
NEXT

I made a section that makes sure the numberis divisible only by 1 and itself. Oh and the formula is only good for primes bigger than 3

[oracle]

Easy to fix: if inputted value is larger than 2 or 3 then output them. But I'm too lazy to rewrite your code :wink: