Jordan’s totient functions

E300758

Jordan’s totient functions are a family of arithmetic functions in number theory that generalize Euler’s totient function to count k-tuples of integers modulo n with certain coprimality conditions.

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Jordan’s totient functions canonical 1

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Statements (48)

Predicate Object
instanceOf family of arithmetic functions
number-theoretic functions
averageOrder ∑_{n≤x} J_k(n) ~ x^{k+1}/((k+1)ζ(k+1))
codomain nonnegative integers
completelyMultiplicative no
convolutionExplanation J_k(n) = ∑_{d|n} μ(d)(n/d)^k
convolutionRelation J_k = μ * id_k
coprimalityCondition J_k(n) counts k-tuples whose gcd with n is 1 in a suitable sense
definitionInformal J_k(n) counts ordered k-tuples of integers modulo n that form a generating set for the additive group Z/nZ
J_k(n) counts ordered k-tuples of integers modulo n whose greatest common divisor with n is 1
DirichletSeries ∑_{n≥1} J_k(n) n^{-s} = ζ(s-k)/ζ(s)
domain positive integers
EulerProduct ∑_{n≥1} J_k(n) n^{-s} = ∏_{p}(1 - p^{k-s})/(1 - p^{-s})
field number theory
generalizes Euler’s totient function
generatingFunctionType Dirichlet generating function
growthRate J_k(n) is of order n^k
introducedBy Camille Jordan
inverseConvolution id_k = 1 * J_k
multiplicative yes
multiplicativeDefinition J_k(mn) = J_k(m)J_k(n) if gcd(m,n)=1
multiplicativeFactor J_k(n)/n^k = ∏_{p|n}(1 - p^{-k})
multiplicativeGroupInterpretation J_k(n) counts k-tuples that generate (Z/nZ,+)
multiplicativeOnCoprimeArguments yes
namedAfter Camille Jordan
primePowerFactorization J_k(n) = n^k ∏_{p|n}(1 - p^{-k})
primePowerFormula J_k(p^a) = p^{ak} - p^{(a-1)k}
relatedConcept Euler product
Möbius function
surface form: Möbius function μ(n)

Riemann zeta function
surface form: Riemann zeta function ζ(s)

identity function id_k(n) = n^k
relationToDivisorFunction J_k is related to the k-th power identity function id_k via Möbius inversion
relationToEulerPhi J_1(n) = φ(n)
specialCase J_1(n) = φ(n)
subfield multiplicative number theory
sumOverDivisorsIdentity ∑_{d|n} J_k(d) = n^k
symbol J_k(n)
topic Dirichlet series of multiplicative functions
arithmetic functions
coprimality in residue classes
usedIn analysis of random k-tuples modulo n
generalizations of Euler’s theorem
probabilistic number theory
study of finite abelian groups
zeta-function identities
valueAtOne J_k(1) = 1
valueAtPrime J_k(p) = p^k - 1
valueAtPrimeSquare J_k(p^2) = p^{2k} - p^k

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Euler’s totient function φ(n) relatedFunction Jordan’s totient functions