Prime factorization conjecture for factorials plus one

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Let S={4,5,7,12,23,229,562}S=\{4,5,7,12,23,229,562\}. A natural number is square-free if no perfect square other than 11 divides it.

Prime factorization conjecture for factorials plus one. For every n∈N∖Sn\in\mathbb N\setminus S, the number n!+1n!+1 is square-free.

The conjecture predicts that the displayed set contains all exceptions to square-freeness for numbers of the form n!+1n!+1. Numerical evidence is reported through n=100n=100, while the further exceptions n=229n=229 and n=562n=562 are explicitly identified in the source; no proof that these are the only exceptions is given.

References

Primary source

William Gerst, “A conjecture on the prime factorization of n!+1”, arXiv:1809.07360 (2018).

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