1分間でなんてとても解けません。 Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...Find the sum of all the even-…

素因数分解 - Wikipedia The prime factors of 13195 are 5, 7, 13 and 29.What is the largest prime factor of the number 600851475143 ? Ruby には便利なライブラリがありますね。 singleton method Integer.prime_division #!/usr/bin/env ruby require…