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Fungrim entry: c24323

∑k=1nlcm⁡ ⁣(n,k)=n2(1+∑d∣ndφ(d))\sum_{k=1}^{n} \operatorname{lcm}\!\left(n, k\right) = \frac{n}{2} \left(1 + \sum_{d \mid n} d \varphi(d)\right)
Assumptions:n∈Z≥0n \in \mathbb{Z}_{\ge 0}
TeX:
\sum_{k=1}^{n} \operatorname{lcm}\!\left(n, k\right) = \frac{n}{2} \left(1 + \sum_{d \mid n} d \varphi(d)\right)

n \in \mathbb{Z}_{\ge 0}
Definitions:
Fungrim symbol Notation Short description
Sum∑nf(n)\sum_{n} f(n) Sum
LCMlcm⁡ ⁣(a,b)\operatorname{lcm}\!\left(a, b\right) Least common multiple
DivisorSum∑k∣nf(k)\sum_{k \mid n} f(k) Sum over divisors
Totientφ(n)\varphi(n) Euler totient function
ZZGreaterEqualZ≥n\mathbb{Z}_{\ge n} Integers greater than or equal to n
Source code for this entry:
Entry(ID("c24323"),
    Formula(Equal(Sum(LCM(n, k), For(k, 1, n)), Mul(Div(n, 2), Add(1, DivisorSum(Mul(d, Totient(d)), For(d, n)))))),
    Variables(n),
    Assumptions(Element(n, ZZGreaterEqual(0))))

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2021-03-15 19:12:00.328586 UTC