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%I #6 Jul 15 2021 09:16:38
%S 1020408163265306122449,4081632653061224489796,9183673469387755102041,
%T 106678449690695619239994950132559020325716449943188991289,
%U 123721752304002019946976391869713420022724403484408534276
%N Numbers k such that the concatenation of 5*k with k gives a square.
%e 5102040816326530612245_1020408163265306122449 = 7142857142857142857143^2.
%Y Cf. A102567, A106497, A115527 - A115556.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, Jan 25 2006
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