Given the sequence a0=1,a1=2,ak+1=ak+ak11+a2k1,k>1 for what value of k occours 52<ak<65 ?

1 Answer
Oct 12, 2017

I used an Excel spreadsheet.

I used column A for my value of k. I entered 0 in cell A1 and I entered =A1+1 in cell A2; this will give me a column of integers incremented by 1 as I copy and block paste the column.

I used column B for my value of ak. I entered 1 in cell B1, 2 in cell B2, and =B2+B1/(1+B1^2) in cell B3; this will give me the recursive calculation as I copy and block paste the column.

The first value of k where 52<ak<65 is:

k=1350,ak=52.01277

The last value of k where 52<ak<65 is:

k=2109,ak=64.98885