Sum (20-3k) for k=4 to 13

algorithmic solution

by Leos Literak

HTML

<script src='https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js?config=TeX-MML-AM_CHTML' async></script>
`sum_(k=4)^13 20-3n` = <span id="result"></span>

JavaScript

var k, sum = 0;
for (k = 4; k <= 13; k++) {
    sum += 20-3*k;
}

// print the result


document.getElementById("result").innerText = sum;