Question 1076020
It's obviously the sum of a geometric sequence with first term 12 and common ratio 0.5=1/2.
The general expression for term number {{{k}}} is
{{{12*(1/2)^(k-1)}}} .
The sum of the 5 terms shown can be written as
{{{sum(12/2^(k-1),k=1,k=5)}}}