SAT Math Practice Question #22459 - SATify | SATify
#22459
sequences and series
exponents
hard
150 sec
Let akk=12011 be the sequence of real numbers defined by a1=0.201, a2=(0.20101)a1, a3=(0.201011)a2, a4=(0.2010101)a3, and in general, ak={(0.20101…011)ak−1(0.20101…01)ak−1if k is odd,if k is even. where the base has k+2 digits. Rearranging the numbers in the sequence akk=12011 in decreasing order produces a new sequence bkk=12011. What is the sum of all integers k, 1≤k≤2011 such that ak=bk?