What is the next number in sequence?
Level
2
What is the next number in the sequence above?
The answer is 1752.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
I struggled a lot with this so i just gave up and searched it.
It turns out that this sequence is made up from the numbers n that are composite and the concatenation of the non-prime natural numbers from 1 to n is a prime number.
Example:
26 is in this sequence because:
- 26 is composite
- The non-prime natural numbers from 1 to 26 are: 1,4,6,8,9,10,12,14,15,16,18,20,21,22,24,25,26 and the concatenation of these numbers (in reverse order) is: and 26252422212018161514121098641 which is a prime number.
The next number of this sequence is 1 7 5 2
Note: The concatenation of two numbers is just taking the numbers and "glueing them together". For example the concatenation of 11 and 27 is: 1127
Resource: I found out about this using THE ON-LINE ENCYCLOPEDIA OF INTEGER SEQUENCES