<PRE><B>Question 178522</B>
I think I finally figured this one out.

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9 is added to each progressive term and 7&#39;s increased by the summation of the number of terms in the sequence   The 7&#39;s part of this sequence is just a play on Gauss&#39;s summation formula.
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so 
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9(n+1)+7n(n+1)/2. n is the number of terms .  You can figure the number of terms by dividing whatever the number of the last term is and subtracting 9 ,then dividing by 7....such as 100 is the last term so subtract 9 and divide by 7...answer is 13......so n would equal 13 
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9(13+1)+7(13)(14)/2=126+637={{{highlight(763)}}}
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you can rewrite the formula to
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(n+1)(9+(7n/2))={{{(n+1)(18+7n)/2}}}
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