Expert: Richard J. Raridon - 12/1/2005

Question
an= lower n like nth power but lower

a1(1 also lower)a1= 9    a11( 11 lower) a11=14

Answer
The standard equation for an arithmetic sequence is
a(n) = a0 +dn
where a0 is the initial term, n is the number of the term and d is the difference between terms.  
In this case, 9 = a0 +d(1) and 14 = a0 +d(11)
so a0 = 8.5 and d = 0.5
and your expression is a(n) = 8.5 +0.5n