Chen's conjectures on inequalities for the Andrews spt-function

Let p(n)p(n) denote the partition function and let spt(n){\mathrm{spt}}(n) denote the smallest-parts function, which counts the smallest parts among the partitions of nn. Chen's conjectures. The following inequalities hold:

  1. For n5n\geq 5,
6πnp(n)<spt(n)<np(n).\frac{\sqrt{6}}{\pi}\sqrt{n}\,p(n)<{\mathrm{spt}}(n)<\sqrt{n}\,p(n).
  1. For (a,b)(2,2)(a,b)\neq(2,2) or (3,3)(3,3),
spt(a)spt(b)>spt(a+b).{\mathrm{spt}}(a)\,{\mathrm{spt}}(b)>{\mathrm{spt}}(a+b).
  1. For n36n\geq 36,
spt(n)2>spt(n1)spt(n+1).{\mathrm{spt}}(n)^2>{\mathrm{spt}}(n-1)\,{\mathrm{spt}}(n+1).
  1. For n>m>1n>m>1,
spt(n)2>spt(nm)spt(n+m).{\mathrm{spt}}(n)^2>{\mathrm{spt}}(n-m)\,{\mathrm{spt}}(n+m).
  1. For n13n\geq 13,
spt(n1)spt(n)(1+1n)>spt(n)spt(n+1).\frac{{\mathrm{spt}}(n-1)}{{\mathrm{spt}}(n)}\left(1+\frac{1}{n}\right)>\frac{{\mathrm{spt}}(n)}{{\mathrm{spt}}(n+1)}.
  1. For n73n\geq 73,
spt(n1)spt(n)(1+π24n3/2)>spt(n)spt(n+1).\frac{{\mathrm{spt}}(n-1)}{{\mathrm{spt}}(n)}\left(1+\frac{\pi}{\sqrt{24}n^{3/2}}\right)>\frac{{\mathrm{spt}}(n)}{{\mathrm{spt}}(n+1)}.

These inequalities concern lower and upper bounds, supermultiplicativity, log-concavity, and ratio inequalities for the spt-function. The paper introduces them as recent conjectures of Chen; the supplied text does not indicate that any of them has been resolved.

Sources & referencesView supporting material

Primary source

Madeline Locus Dawsey and Riad Masri, “Effective Bounds for the Andrews spt-function”, arXiv:1706.01814 (2019).

Additional references

2 papers in this index state this conjecture (2013–2017). The statement above is taken from the most recent of them; the others are arXiv:1310.7982.

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