What is N?

Level 1

Below is a number pattern.
2, 3, 5, 9, 17, 33, 65, 129, N, 513
What number should "N" be?


The answer is 257.

Anthony Teo by Anthony Teo , 21, Netherlands

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7 solutions

Emrul Kais
Mar 2, 2014

nth term of this series is : (2^(n-1))+1

2 Helpful 0 Interesting 0 Brilliant 0 Confused
Saurav Sah
Mar 7, 2014

The series goes in : 2n-1.So 129*2-1=257

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Rahul Suresh
Mar 1, 2014

Add the each number with the preceding number and so on...

2

2+1=3

5+4=9

9+8=17

33+32=65

65+64=129

129+128= 257

257+256=513

1 Helpful 0 Interesting 0 Brilliant 0 Confused

2^n+1is the number representation in the series given. n is the location from 0. for n=6 x=257. else 2^(n-1)+1. n starts from 1 or is position in the series. then n=7.

Vishnupramod Maddirela - 7 years, 2 months ago

2+1=3 3+2=5 5+4=9 9+8=17 17+16=33 33+32=65 65+64=129 129+128=257

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Mehdi Balti
Oct 7, 2015

Just multiply predecessor with 2 and the given result minus by 1.

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Abhi Nandan
Oct 23, 2014

the series is

+1 ,+2+4,+8,+16,+32 ........

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Danish Parmar
May 23, 2014

2*3=6-1=5

2*5=10-1=9

2*9=18-1=17

2*17=34-1=33

2*33=66-1=65

2*65=130-1=129

2*165=258-1=257

2*257=514-1=513

Hence, N = 257

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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