11028 - Sum of Product

[lovemagic]

ooops.......

the net says a sequence.to tough to imagine!!!!!!!(for me)

[windows2k]

the net says a sequence.to tough to imagine!!!!!!!(for me)

Hello, every body.
I don't know how to solve the problem.
How should I find the related resource to solve the problem?
Thx

[lovemagic]

i tried but couldnt solve the problem.then i searched in the board & found a site given
http://www.research.att.com/~njas/sequences/

there,i got the formula.but i havnt understood yet how it is derived....

[Rocky]

thank's i also got the formulla...
but need to know the derivetion....
any help ?????

Thank's in Advance
Rocky

[sakhassan]

Is This the formula ???

F = 3*F[i-1] - F[i-2];

I got the following outputs for 2 - 22

Code: Select all

Case #1: 0
Case #2: 1
Case #3: 3
Case #4: 8
Case #5: 21
Case #6: 55
Case #7: 144
Case #8: 377
Case #9: 987
Case #10: 2584
Case #11: 6765
Case #12: 17711
Case #13: 46368
Case #14: 121393
Case #15: 317811
Case #16: 832040
Case #17: 2178309
Case #18: 5702887
Case #19: 14930352
Case #20: 39088169
Case #21: 102334155

r they correct ????

[mrahman]

hi sakhassan

your formula is wrong. There is two formula. One for Odd number, other for even number. The input 21 and 22 is invalid.
here is the output for 2-20

Code: Select all

Case #1: 1
Case #2: 1
Case #3: 3
Case #4: 8
Case #5: 21
Case #6: 43
Case #7: 69
Case #8: 102
Case #9: 145
Case #10: 197
Case #11: 261
Case #12: 336
Case #13: 425
Case #14: 527
Case #15: 645
Case #16: 778
Case #17: 929
Case #18: 1097
Case #19: 1285

Good Luck!

[sakhassan]

Thanks Buddy ! I got it

[sakhassan]

I got the formula tooo

[DELETED BY MODERATOR]

[little joey]

No spoilers please!!
I removed them from your message, sakhassan.

[mak(cse_DU)]

while trying to formulate,i have got one,i dont know its right or wrong.fibonacci comes with every 2nd integer f the sequence.

for,
n=3 ans=1
n=4,ans=3
n=5,ans=8
n=6,ans=21

m i right here???

what's the ans for n=1 & n=2???
i think in both case the ans will be 1.

plz response...

n........... fun(n)
2...........1
3........... 1
4........... 3
5........... 8
6........... 21
7........... 43
8........... 69
see the correct sequence. I hope you will try google.
from the problem description n>1