All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars
 perplexus dot info

 A bizarre sequence (Posted on 2003-07-28)
Here's a sequence:

2, 4, 8, 13, 20, 29, _, _.

What numbers go into the blanks, and what is the rule for the sequence?

 See The Solution Submitted by Lewis Rating: 3.5000 (4 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
 Puzzle Solution Comment 14 of 14 |

`Let the pth term of the sequence be S(p).`
`Then, S(p) = F(p) + T(p), where:`
`F(p) = pth term of the Fibonacci SequenceT(p) = pth triangular number`
`We thus set up the following table:`
`p   F(p)   T(p)    S(p)`
`1    1       1      2 `
`2    1       3      4`
`3    2       6      8 `
`4    3      10     13 5    5      15     20 `
`6    8      21     29`
`7    13     28     41`
`8    21     36     57`
`Accordingly, S(7) = 41, S(8) = 57, and consequently:`
`The required numbers that go into the blanks are 41 and 57.`

Edited on April 1, 2008, 12:26 pm
 Posted by K Sengupta on 2008-04-01 12:26:14

 Search: Search body:
Forums (0)