JavaScript Program to Generate Number Sequence

function countAndSay(n) {
    
    // Base case: the first term is always "1"
    let result = "1";

    // Iteratively generate each term starting from the second term
    for (let i = 1; i < n; i++) {
        let temp = "";
        let count = 1;

        // Iterate through each digit in the current term
        for (let j = 1; j < result.length; j++) {
            
            // If the current digit is the same as the 
            //previous one, increment the count
            if (result[j] === result[j - 1]) {
                count++;
            } else {
                
                temp += count + result[j - 1];
                count = 1; 
            }
        }

        // Append the count and the last digit
        temp += count + result[result.length - 1];

        // Update the result to the newly generated term
        result = temp;
    }

    // Return the nth term of the sequence
    return result;
}

// Example usage
const n = 5;
console.log("The " + n + "th term of the Count and Say sequence is: 
            " + countAndSay(n));

function countAndSayRecursive(n) {
    
    // Base case: the first term is always "1"
    if (n === 1) {
        return "1";
    }

    // Recursive call to generate the 
    // (n-1)th term of the sequence
    const prev = countAndSayRecursive(n - 1);

    let temp = "";
    let count = 1;

    // Iterate through each digit of the (n-1)th term
    for (let i = 1; i < prev.length; i++) {
        
        if (prev[i] === prev[i - 1]) {
            count++;
        } else {

            temp += count + prev[i - 1];
            count = 1;
        }
    }

    // Append the count and the last digit to the temporary result
    temp += count + prev[prev.length - 1];

    // Return the newly generated term
    return temp;
}

// Example usage
const n = 5;
console.log("The " + n + 
            "th term of the Count and Say sequence (recursive approach) is: "
            + countAndSayRecursive(n));

function countAndSay(n) {
    if (n === 1) return "1";
    let sequence = ["1"];
    for (let i = 1; i < n; i++) {
        let prevTerm = sequence[i - 1];
        let nextTerm = "";
        let count = 1;
        for (let j = 1; j < prevTerm.length; j++) {
            if (prevTerm[j] === prevTerm[j - 1]) {
                count++;
            } else {
                nextTerm += count + prevTerm[j - 1];
                count = 1;
            }
        }
        nextTerm += count + prevTerm[prevTerm.length - 1];
        sequence.push(nextTerm);
    }
    return sequence[n - 1];
}
console.log(countAndSay(3));
console.log(countAndSay(5));
console.log(countAndSay(8));