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%I A271637 #27 Jun 14 2021 11:53:14
%S A271637 6,820,104391567,119304648,858993460,900719925474100,
%T A271637 26202761468337432,29478106651879611,32753451835421790,
%U A271637 225701339254799219773,243062980735937621294,260424622217076022815,277786263698214424336,944473296573929042740,232485734541274841289650
%N A271637 Squared-squares in base 2: numbers n such that n^2 in base 2 is of the form xx for a string x.
%C A271637 The base-2 expansion must be canonical (not start with leading zeros).
%C A271637 The sequence is infinite, as (4/5)*(2^(20*k + 10) + 1) has the property for k >= 0.
%D A271637 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.
%H A271637 Giovanni Resta, <a href="/A271637/b271637.txt">Table of n, a(n) for n = 1..398</a>(terms < 2^270)
%H A271637 Andrew Bridy, Robert J. Lemke Oliver, Arlo Shallit, Jeffrey Shallit, <a href="https://arxiv.org/abs/1707.03894">The Generalized Nagell-Ljunggren Problem: Powers with Repetitive Representations</a>, arXiv:1707.03894 [math.NT], 2017. See p. 10.
%e A271637 The number 6 is in the sequence because 36 = 6^2 and 36 in base 2 is 100100, which is xx for x = 100.
%Y A271637 The base-2 analog of A106497.
%K A271637 nonn
%O A271637 1,1
%A A271637 _Jeffrey Shallit_, Apr 11 2016
%E A271637 a(7)-a(15) from _Giovanni Resta_, Apr 11 2016

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