SOLUTION: How many prime numbers less than 200 are 1 more than the square of an integer?

Question 344426: How many prime numbers less than 200 are 1 more than the square of an integer?
Found 2 solutions by Alan3354, vleith:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Check the even numbers from 2 to 14
Square them and add 1
2 --> 5
4 --> 17
etc

Answer by vleith(2983) (Show Source): You can put this solution on YOUR website!
Trial and error. Easiest to do squares and then test
1^2 = 1 1+1 = 2 2 is prime
2^2 = 4 4+1 = 5 5 is prime
3^2 = 9 9+1=10 --> not prime
4^2 = 16 16+1 = 17 17 is prime
Just keep doing that.
After a few odd numbers, you'll see that odd squared +1 is even, which cannot be prime.
14*14 is just below 200, so you only need to do even integers from 6 thru 14 and test them
If you don't know what numbers are prime, look here
http://www.math.utah.edu/~pa/math/primelist.html
You can do it from here
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