Question

a sequence problem #2

Answer 1

why Tomas?

Answer 2

not for me :P

Answer 3

problem...??

Answer 4

lol :D

Answer 5

I am 'Fool' as a proper noun.

Answer 6

will there be part for my problem? LOL

Answer 7

Post it ...!!!

Answer 8

This is the problem:
The sequence
\[1,2,1,2,2,1,2,2,2,1,2,2,2,2,1,2,2,2,2,2,1,2,...\]
consists of 1's separated by blocks of 2's with n 2's in the nth block.
The sum of the first 1234 terms of this sequence is...
a.1996 b.2419 c.2429 d.2439

Answer 9

WRONG!!!! LOL

Answer 10

Tomas, trivial guessing technique don't work always :P

Answer 11

2439

Answer 12

This reminded me of Riordan array, ( http://oeis.org/A114284)

Answer 13

what's that?

Answer 14

so whats the answer

Answer 15

It's not about the answer, it's about the approach.

Answer 16

actually its about both

Answer 17

Every n(n+1)/2 term of the sequence is 1 and the others is 2.

Answer 18

yes

Answer 19

b.2419 is the answer.

Answer 20

There are exactly 49 numbers of the form n(n+1)/2 in the sequence and then the rest is easy to figure out ;)

Answer 21

CORRECT!!! LOL

Answer 22

keep up good work guy :)

Answer 23

MrBank, task for you, find a closed form for the nth term of this sequence and the sum of the nth term too.;)

Answer 24

For that \[a _{(n/2)*(n+1)}=1\]
in x terms,we will find the nearest term for 1 by
(n/2)*(n+1)=x ----> we get an n. may be an integer or a decimal.
if it's a decimal you chose an integer that is less than that number.
that we know, 1 has n term in x term

For the sum of x term,
Sx=2x-n

DONE!! lol
if i'm not wrong

Answer 25

@Mr Bank, this is not a closed form.