1.5, 2.25, 3.375, 5.0625, 7.59375... and so on
<span><span>The sum of a squared and b is given by

</span>7 times the sum of a squared and b is given by
</span><span>
while 4 times the sum of a squared and b is given by
</span>

Therefore, <span>7 times the sum of a squared and b minus 4 times the sum of a squared and b is given by

</span>