Sum of sequence
Posted:
Wed Apr 17, 2013 9:49 pmby 16422
1 + 2 + 5 + 13 + ... + 89 + 233 = ____________
Aren't the differences between the terms the odd fibonacci numbers? So, +1, +3, +8, +21, +55, +144.
How do add this sequence without summing it up in your head?
Re: Sum of sequence
Posted:
Wed Apr 17, 2013 9:57 pmby 16422
And also this one:
5+7+12+19+31+ ... +131+212= ________________
~Thanks :)
Re: Sum of sequence
Posted:
Wed Apr 17, 2013 10:06 pmby Fredfredburger
For the first one, the sum of the sequence of the odd fibonacci terms is simply the next term after the last term. Here the term after 233 is 377(233+144), your sum.
For the second it's is a fibonacci type sequence. The sum of a fibonacci sequence is the 2nd term after the last one you have minus the second term.
Here the first term after is 131+212=343
The second term is 343+212=555
555-7=548