Try This Number Theory Problem

What comes next in this sequence:

2 , 3 , 5 , 7 , 11 , 13 , 17 , ? ? ? 2, 3, 5, 7, 11, 13, 17, ???

20 18 21 19

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6 solutions

Calvin Lin Staff
Jun 26, 2014

The sequence is a list of primes, and the next prime is 19.

The image demonstrates the sieve of Eratosthenes, where multiples of 2 (except 2 itself) are removed with a blue vertical line, multiples of 3 (except 3 itself) are removed with a orange horizontal line, multiples of 5 (except 5 itself) are removed with a green diagonal line and multiples of 7 (except 7 itself) are removed with a purple vertical line. This process continues for each prime that you come across.

Can't we say its just sequence of prime numbers? Simply

Sai Krishna Yetukuri - 6 years, 11 months ago

nice one boy!

Agustin Peñalosa Jr. - 6 years, 11 months ago

Typo: 19 not 29

Nathan Ramesh - 6 years, 11 months ago
Muhammad Ihsan
May 9, 2015

i just see the image

For problems with images, if you scroll down you will see more of the text.

Same applies to problems with a lot of text.

Calvin Lin Staff - 6 years, 1 month ago
Aashish Patel
Jul 19, 2014

These all numbers are prime numbers.

Prince Mishra
Jul 8, 2014

19 is prime number which comes after 17 and this given sequence is of prime number

Nathan Blanco
Jul 1, 2014

The numbers are prime numbers. If needed, you just need to count up until you find a number that has no factors, which is 19. As for the picture, I have no idea what that is though it leaves the prime numbers blank, giving you the answer.

Charity Aghahowa
Jun 30, 2014

Obviously it is the next number in the diagram that is not crossed out!!! 19!!

Well said .

Sai Krishna Yetukuri - 6 years, 11 months ago

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