英和和英

発音

名詞

amicable number (plural amicable numbers)

1. (number theory) One of a pair of numbers having the property that the sum of the divisors of each, excluding itself, is equal to the other number.

   The factors of 220, excluding 220 itself, are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110 and sum to 284; the factors of 284, excluding 284 itself, are 1, 2, 4, 71, and 142, and sum to 220; hence 220 and 284 are amicable numbers.

参考

• abundant number
• deficient number
• perfect number
• sociable numbers