Hardy–Ramanujan asymptotic formula

E123877

The Hardy–Ramanujan asymptotic formula is a landmark result in number theory that gives an approximate expression for the partition function p(n), describing how the number of integer partitions of n grows rapidly with n.

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Predicate Object
instanceOf asymptotic formula
result in number theory
theorem in analytic number theory
appliesTo integer partitions
partition function p(n)
approximationQuality asymptotically accurate as n \to \infty
authors G. H. Hardy
Srinivasa Ramanujan
classification asymptotic expansion of arithmetic function
describes asymptotic growth of the partition function p(n)
domainOfVariable n \in \mathbb{N}
field analytic number theory
number theory
gives approximate expression for p(n)
givesLeadingTerm \frac{1}{4n\sqrt{3}} e^{\pi \sqrt{2n/3}}
growthType subexponential in n but superpolynomial
hasAsymptoticNotation p(n) \sim f(n) as n \to \infty
hasConstant \pi\sqrt{2/3}
hasDenominatorFactor 4n\sqrt{3}
hasErrorTerm relative error tends to 0 as n \to \infty
historicalSignificance early major application of the circle method
implies log p(n) grows on the order of \sqrt{n}
improvedBy Hardy–Ramanujan asymptotic formula self-linksurface differs
surface form: Rademacher convergent series for p(n)
inspired further work on partition asymptotics
involvesConcept asymptotic analysis
circle method
integer partitions
involvesFunction partition function p(n)
isLandmarkResultIn partition theory
mainExpression p(n) \sim \frac{1}{4n\sqrt{3}} e^{\pi \sqrt{2n/3}}
methodIntroducedWith Hardy–Littlewood circle method
namedAfter G. H. Hardy
Srinivasa Ramanujan
publishedIn Proceedings of the London Mathematical Society
refinedBy Rademacher exact formula for p(n)
relatedTo generating function of p(n)
modular forms
q-series
shows p(n) grows rapidly with n
showsBehavior p(n) grows roughly like e^{C\sqrt{n}} for C = \pi\sqrt{2/3}
topicOf expositions in analytic number theory textbooks
research in additive number theory
usedFor estimating p(n) for large n
usedIn combinatorics
statistical mechanics models involving partitions
usesGeneratingFunction \sum_{n \ge 0} p(n) q^n = \prod_{m \ge 1} (1 - q^m)^{-1}
yearProved 1918

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Referenced by (5)

Full triples — surface form annotated when it differs from this entity's canonical label.

G. H. Hardy knownFor Hardy–Ramanujan asymptotic formula
Hardy knownFor Hardy–Ramanujan asymptotic formula
subject surface form: G. H. Hardy
Hardy–Ramanujan asymptotic formula improvedBy Hardy–Ramanujan asymptotic formula self-linksurface differs
this entity surface form: Rademacher convergent series for p(n)
Godfrey notableFor Hardy–Ramanujan asymptotic formula
subject surface form: G. H. Hardy
Godfrey notableFor Hardy–Ramanujan asymptotic formula
subject surface form: G. H. Hardy
this entity surface form: Hardy–Ramanujan theorem