Say for the recursive formula 2, 5, 9, 19 , 37...(adsbygoogle = window.adsbygoogle || []).push({});

Instead of writing it as a_{n}= a_{n-1}+ * 2 a_{n-2}

can you write it as:

a_{n}= 2a_{n}+ (-1)^{n}

Just double checking. I encountered this earlier helping someone and I haven't done recursive formulas in a while..

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# Is this acceptable in recursive formulas?

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