Pascal Triangle PRIMES
Level
pending
Find the number of prime numbers from row 1 to row 25 inclusive of a Pascal Triangle.
Clarifications
For example, the number of prime numbers from row 1 to 4 is 3. The prime numbers are 2, 3, 3.
The answer is 17.
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
Due to the nature of Pascal's Triangle, the only numbers that can be prime are those adjacent to a one. In a given row, these numbers are equivalent to the row number, so the question is essentially asking how many prime numbers are between 1 and 25. There are 9 prime numbers that satisfy this condition, and there are two of each in every row, except in the second row as 2 only appears once. 8(2) + 1 = 17.