Journal of Integer Sequences, Vol. 29 (2026), Article 26.3.1

Some 2-adic Integers Related to the Odd Part of 2e!


Donald M. Davis
Department of Mathematics
Lehigh University
Bethlehem, PA 18015
USA

Abstract:

The odd part of 2e! as e → ∞ leads to a 2-adic integer z. The bits of z were publicized in OEIS sequence A359349, where two conjectures were made, relevant to computing z. We prove both of those conjectures. A second 2-adic integer, the limit of ((2e-1)!!–1)/2e, plays a key role in one proof.


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(Concerned with sequence A359349.)


Received October 30 2025; revised version received May 7 2026; May 10 2026. Published in Journal of Integer Sequences, May 15 2026.


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