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| 1 | +/* |
| 2 | + A program to calculate the Aliquot Sum of a number. |
| 3 | + The aliquot sum of a number n, is the sum of all the proper divisors of n apart from n itself |
| 4 | + For example, for the number 6 |
| 5 | + The divisors are 1, 2, 3 (we don't consider 6), so its aliquot sum is 1 + 2 + 3 = 6 |
| 6 | + 1 is the only number whose aliquot sum is 0 (since its only divisor is 1 and aliquot sum of a number couldn't have itself) |
| 7 | + For all prime numbers, the aliquot sum is 1, since their only divisor apart from themselves is 1 |
| 8 | + Article on Aliquot Sum: https://en.wikipedia.org/wiki/Aliquot_sum |
| 9 | + */ |
| 10 | + |
| 11 | +/** |
| 12 | + * @param {Number} input The number whose aliquot sum you want to calculate |
| 13 | + */ |
| 14 | +function aliquotSum (input) { |
| 15 | + // input can't be negative |
| 16 | + if (input < 0) throw new TypeError('Input cannot be Negative') |
| 17 | + |
| 18 | + // input can't be a decimal |
| 19 | + if (Math.floor(input) !== input) throw new TypeError('Input cannot be a Decimal') |
| 20 | + |
| 21 | + // Dealing with 1, which isn't a prime |
| 22 | + if (input === 1) return 0 |
| 23 | + |
| 24 | + let sum = 0 |
| 25 | + for (let i = 1; i <= (input / 2); i++) { |
| 26 | + if (input % i === 0) sum += i |
| 27 | + } |
| 28 | + |
| 29 | + return sum |
| 30 | +} |
| 31 | + |
| 32 | +export { aliquotSum } |
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