What kind of sequence is this 161, 145, 129, 113

145-161=129-145=113-129=-16

There is a common difference of - 16 between each term and the term preceding it, which is the defining characteristic of an arithmetic sequence.

First step to solve this problem, would be to find out what the sequence subtracts in each jump.

Between 161 and 145 there are 16

between 145 and 129 there are 16

And between 129 and 113 there are 16.

Things are showing us this is a Arithmetic Sequence as each time you jump one step forward the a_n = a_ (n-1) - 16.

Therefore the correct answer would be to say it is an Arithmetic Sequence