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Math Help - [SOLVED] help with writing a recursive formula for a sequence

  1. #1
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    [SOLVED] help with writing a recursive formula for a sequence

    i need to write a recursive formula for the nth term of the sequence:
    2, 5, 7, 12, 19, 31,...
    i can see the pattern they are increasing by but i'm horrible at figuring out how to put it into a formula... i just know how to set it up:
    a_1=2 a_n=...?
    any advice on how to start?
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  2. #2
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    Hello, e____o!

    i need to write a recursive formula for the nth term of the sequence:
    . . 2, 5, 7, 12, 19, 31, ...

    i can see the pattern they are increasing by . . . . you can?

    It's a Fibonacci sequence . . .

    Each term is the sum of the preceding two terms: . a_n \:=\:a_{n-1} + a_{n-2}

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  3. #3
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    haha, well i thought i could see the pattern...
    ok yea once i see the formula i realize how obviously easy it is XD but we never learned about a fibonacci sequence, maybe that's why? anyway thanks so much for your help!
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