The two-term supercongruence conjecture for the original sporadic sequences

From papers

Let A(n)A(n) be one of the 15 original sporadic sequences. For a prime p5p\geq 5 and integers m,r1m,r\geq 1, write

A(mpr)A(mpr1)(modpλr).A(mp^r) \equiv A(mp^{r-1}) \pmod{p^{\lambda r}}.

Here λ=3\lambda=3 except for the sequences B\bf{B}, C\bf{C}, E\bf{E}, F\bf{F} and s18s_{18}, for which λ=2\lambda=2.

Two-term supercongruence conjecture. For all primes p5p\geq 5 and all integers m,r1m,r\geq 1,

A(mpr)A(mpr1)(modpλr).A(mp^r) \equiv A(mp^{r-1}) \pmod{p^{\lambda r}}.

The conjecture concerns the arithmetic properties of the 15 sporadic sequences, which arise from three-term recurrences and have modular parametrizations, binomial-sum representations and geometric origins. The paper states that this is the original conjecture and proves the last remaining case, so the claim is solved.

Progress summary

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Sources & referencesView supporting material

Primary source

Brendan Alinquant and Robert Osburn, “On sporadic sequences”, arXiv:2312.07134 (2024).

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