Pennies per day (by day count) in Clojure:

(defn pennyPerDay [numDays]
  (reduce + (range 1 (+ numDays 1)))
)

(pennyPerDay 30)

Pennies per day (by day count) in JS:

function pennyPerDay(numDays) {
  return Array(++numDays)
    .fill(0)
    .reduce((sum, _, i) => sum + i, 0);
}

pennyPerDay(30);

Most frequent terms in JS:

const termList = ['term1', 'term2', 'term3', 'term3'];
function mostFrequentTerms(arr) {
  return arr.reduce((result, curr) => {
    result[curr] = ++result[curr] || 1
    return result;
  }, {})
}
  
mostFrequentTerms(termList);

Most frequent terms in a list with Clojure:

(def term-list [:term1 :term2 :term3 :term3])
(defn most-freq-terms \[terms\]
  (->> terms
       frequencies
       (sort-by val)
       reverse))
(most-freq-terms term-list)