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%I #6 Jul 15 2021 09:17:09
%S 17728531856,27700831025,39889196676,54293628809,70914127424,
%T 89750692521,32653061224489796,73469387755102041,
%U 1245674740484429065743944636678200692041522491349481
%N Numbers k such that the concatenation of 4*k with k gives a square.
%e 70914127424_17728531856 = 84210526316^2.
%Y Cf. A102567, A106497, A115527 - A115556.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, Jan 25 2006
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