Conjectured quartic-invariant inequalities for the distinct partition function

Let q(n)q(n) denote the number of partitions of nn into distinct parts, and set an=q(n)a_n=q(n). For a quartic binary form, define

A(a0,a1,a2,a3,a4)=a0a44a1a3+3a22,A(a_0,a_1,a_2,a_3,a_4)=a_0a_4-4a_1a_3+3a_2^2, B(a0,a1,a2,a3,a4)=a0a2a4+a23+a0a32+a12a42a1a2a3,B(a_0,a_1,a_2,a_3,a_4)=-a_0a_2a_4+a_2^3+a_0a_3^2+a_1^2a_4-2a_1a_2a_3, I(a0,a1,a2,a3,a4)=A(a0,a1,a2,a3,a4)327B(a0,a1,a2,a3,a4)2.I(a_0,a_1,a_2,a_3,a_4)=A(a_0,a_1,a_2,a_3,a_4)^3-27B(a_0,a_1,a_2,a_3,a_4)^2.

The quartic-invariant conjecture for q(n)q(n). The following inequalities hold:

A(an1,an,an+1,an+2,an+3)>0for n230,A(a_{n-1},a_n,a_{n+1},a_{n+2},a_{n+3})>0\quad\text{for }n\geq230, B(an1,an,an+1,an+2,an+3)>0for n272,B(a_{n-1},a_n,a_{n+1},a_{n+2},a_{n+3})>0\quad\text{for }n\geq272,

and

I(an1,an,an+1,an+2,an+3)>0for n267.I(a_{n-1},a_n,a_{n+1},a_{n+2},a_{n+3})>0\quad\text{for }n\geq267.

These are proposed as analogues for the distinct partition function of quartic-binary-form invariant inequalities previously studied for the ordinary partition function. The supplied text gives no resolution of these conjectures.

Sources & referencesView supporting material

Primary source

Janet J. W. Dong and Kathy Q. Ji, “Higher Order Turan Inequalities for the Distinct Partition Function”, arXiv:2303.05243 (2023).

Additional references

2 papers in this index state this conjecture (2018–2023). The statement above is taken from the most recent of them; the others are arXiv:1805.05196.

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