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%I #24 Jan 16 2024 11:08:11
%S 16,25,36,49,64,81,100,121,144,225,400,441,484,676,900,1444,10000,
%T 40000,44944,90000,1000000,4000000,9000000,100000000,400000000,
%U 900000000,10000000000,40000000000,90000000000,1000000000000,4000000000000,9000000000000,100000000000000
%N Perfect squares whose decimal expansion consists of k > 1 digits, k-1 of which are equal.
%C The terms > 90000 are of one of the following three forms: 10^(2*j), 4*10^(2*j) or 9*10^(2*j) where j is an integer >= 3.
%C See Gica/Panaitopol link for proof of above comment. - _Ray Chandler_, Jan 16 2024
%H Ray Chandler, <a href="/A368049/b368049.txt">Table of n, a(n) for n = 1..1000</a>
%H Alexandru Gica and Laurențiu Panaitopol, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL6/Panaitopol/panaitopol41.html">On Oblath's Problem</a>, J. Integer Seq., Vol. 6 (2003), article 03.3.5, 12 pp.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,100).
%F a(n) = 100*a(n-3) for n > 22. - _Stefano Spezia_, Dec 09 2023
%Y Cf. A235717, A018885.
%Y Subsequence of A000290.
%K nonn,base,easy
%O 1,1
%A _José Hernández_, Dec 09 2023