# 1,2,3,5,16 , What is next ?

#### Mark Haynes Profile Answers by Mark Haynes Questions by Mark Haynes

• Mar 2nd, 2012

231 ... there are several ways to come up with different next numbers in the series, this just seems the best as the formula to get it works on the whole series.

1 = abs((0^2) - (-1^2))
2 = abs((1^2) - (0^2))
3 = abs((2^2) - (1^2))
5 = abs((3^2) - (2^2))
16 = abs((5^2) - (3^2))
231 = abs((16^2) - (5^2))

Im guessing there are other possible answers out there.

#### amar agarwal

• Apr 2nd, 2012

#### javahrishi Profile Answers by javahrishi

• Apr 6th, 2012

2^2 - 1^2=3;
3^2 - 2^2=5;
5^2 - 3^2=16;
16^2 - 5^2 = 231

#### sasikumar

• Apr 7th, 2012

1+0*1;
1+1*1=2;
2+1*1=3;
3+2*1=5;
5+3*2*1=16;
16+5*3*2*1=126

#### rekharajan

• Jun 29th, 2012

16*5-1=79

#### Rohit

• Aug 24th, 2012

Explanation:
Add prev 2 numbers (16+5), if the result is a prime number then the answer is the prime number, else it is twice of the result number (16+5=21, 21*2=42).

#### Naira

• Nov 1st, 2020

2²-1² = 3 (4-1=3)
3²-2² = 5 (9-4=5)
5²-3² = 16 (25-9=16)
16²-5² = 231 (256-25=231)  