The conjectures on 4-adic valuations of colored 4-ary partition functions

From papers

Let Sk,m(n)S_{k,m}(n) be the nnth coefficient in the power-series expansion defining the mm-colored kk-ary partition function, and define

φk(n)=max{sN:ksn},φk(0)=+.\varphi_k(n)=\max\{s\in\mathbb{N}:k^s\mid n\},\qquad \varphi_k(0)=+\infty.

4-adic valuation conjectures. The following claims are conjectured: (1) If m6(mod8)m\equiv6\pmod 8, then (φ4(S4,m(n)))nN(\varphi_4(S_{4,m}(n)))_{n\in\mathbb{N}} is unbounded. (2) If m≢6(mod8)m\not\equiv6\pmod 8, then this sequence is 4-automatic. (3) With an=φ4(S4,1(n+1))a_n=\varphi_4(S_{4,1}(n+1)), the listed initial values and recurrences hold. (4) With bn=φ4(S4,2(n+1))b_n=\varphi_4(S_{4,2}(n+1)), the listed initial values and recurrences hold. (5) For sN2s\in\mathbb{N}_{\geq2},

ν2(S4,2s(n))=s+1+(ν2(2n)(mod2)),\nu_2(S_{4,2^s}(n))=s+1+(\nu_2(2n)\pmod2),

and the stated formula for φ4(S4,2s(n))\varphi_4(S_{4,2^s}(n)) follows. (6) For sN3s\in\mathbb{N}_{\geq3} and mNm\in\mathbb{N},

φ4(S4,2sm+2s1(n))=φ4(S4,2s1(n)).\varphi_4(S_{4,2^sm+2^{s-1}}(n))=\varphi_4(S_{4,2^{s-1}}(n)).

These numerical predictions concern automaticity, unboundedness, and explicit valuation recurrences for the first composite base case; no resolution is given.

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Sources & referencesView supporting material

Primary source

Maciej Ulas and Błażej Żmija, “On p-adic valuations of certain m colored p-ary partition functions”, arXiv:1904.03398 (2019).

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