두교 체 [HDU 5608] function Problem Description There is a function f(x),which is defined on the natural numbers set N,satisfies the following eqaution N2−3N+2=∑d|Nf(d) N 2 − 3 N + 2 = ∑ d | N f ( d ) calulate ∑ni=1f(i) mod 109+7 ∑ i = 1 n f ( i ) ... 수론두교 체
[HDU 5608] function Problem Description There is a function f(x),which is defined on the natural numbers set N,satisfies the following eqaution N2−3N+2=∑d|Nf(d) N 2 − 3 N + 2 = ∑ d | N f ( d ) calulate ∑ni=1f(i) mod 109+7 ∑ i = 1 n f ( i ) ... 수론두교 체