A little puzzle
 

Hello,
I thought I would give the forum a little puzzle that I made :)


Here is the puzzle :

What do the numbers 3, 4, 5, 9, 10 and 15 have in common?

Have fun solving :)

OEIS sequence A217040? Bases b in which the increasing concatenation of all primes smaller than b forms a prime number.

Well done!

[QUOTE=R2357;559596]Well done![/QUOTE]

:banana: Well, that was quick... Another one, please!

3, 4, 9, 8, 9, 9, 8, 9, 9, 8...

[QUOTE=R2357;559590]Hello,
I thought I would give the forum a little puzzle that I made :)


Here is the puzzle :

What do the numbers 3, 4, 5, 9, 10 and 15 have in common?

Have fun solving :)[/QUOTE]

They are all divisors of 360 (the number of degrees in a turn)

[QUOTE=Uncwilly;559602]3, 4, 9, 8, 9, 8...[/QUOTE]

I will gues OEIS A239384 - (Decimal expansion of the probability of a normal-error variable exceeding the mean by more than three standard deviations), however it's most probably not correct, since you now know I search in OEIS.

[QUOTE=Viliam Furik;559604]I will gues OEIS A239384[/QUOTE]That sequence starts with 1. I made an error. I have now corrected the sequence.

oeis won't help you for this one:


4, 11,14, 17

[QUOTE=a1call;559614]oeis won't help you for this one:


4, 11,14, 17[/QUOTE]

Hint: They are all consecutive integers n for which f[SUB]1[/SUB](n) and f[SUB]2[/SUB](n) are Twin-Prime-Pairs.:smile:

Another riddle :)
 

[QUOTE=Viliam Furik;559598]:banana: Well, that was quick... Another one, please![/QUOTE]


Here goes, what do pi and the prime number sequence have in common (apart from pi's usage in the prime counting function and in the Gapcoin symbol)?