A020340 Least square base n doublet (written in base 10).

36, 4, 378225, 7056, 14393520729, 16, 9, 557904400, 1322314049613223140496, 36, 613401598811409576100, 321418490709904, 837225, 16, 7535664872989640713426833504575377836025, 36, 16900, 100, 7112889

Offset

2,1

Comments

In Bridy et al. it is shown how to construct infinitely many examples for any given base n >= 2. - Jeffrey Shallit, Jun 14 2021

References

Andrew Bridy, Robert J. Lemke Oliver, Arlo Shallit, and Jeffrey Shallit, The Generalized Nagell-Ljunggren Problem: Powers with Repetitive Representations, Experimental Math, 28 (2019), 428-439.

David Wells, "The Penguin Dictionary of Curious and Interesting Numbers", Revised Edition 1997, p. 189.

Links

Table of n, a(n) for n=2..20.

Andrew Bridy, Robert J. Lemke Oliver, Arlo Shallit, and Jeffrey Shallit, The Generalized Nagell-Ljunggren Problem: Powers with Repetitive Representations, preprint arXiv:1707.03894 [math.NT], July 14 2017.

A. Ottens, The arithmetic-digits-squares-three.digits problem

Crossrefs

Cf. A020339, A054214, A054215, A054216, A030465, A030466, A030467.

Sequence in context: A285575 A227168 A100252 * A255868 A289138 A181759

Adjacent sequences: A020337 A020338 A020339 * A020341 A020342 A020343

Keyword

base,nonn

Author

David W. Wilson

Status

approved