OFFSET
1,1
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.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
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.
EXAMPLE
For example, for b = 18, we have y = 49, and the base-b representation of y^2 is 777.
MATHEMATICA
r[b_] := Reduce[0 < x < b && y > 0 && y^2 == x + b x + b^2 x, {x, y}, Integers]; Reap[For[b = 2, b < 12000, b++, If[r[b] =!= False, Print[b]; Sow[b]]]][[2, 1]] (* Jean-François Alcover, Jul 23 2017 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jeffrey Shallit, Jul 23 2017
STATUS
approved