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Numbers whose square is the concatenation of two numbers k and k-9.
11

%I #5 Jun 18 2021 18:09:29

%S 71,7235,9701,798981,997001,35324118,64675883,99970001,3297392379,

%T 6702607622,7890726434,8812181189,9999700001,897807218979,

%U 917811219179,979998999801,999997000001,46193210013657,49751928874867

%N Numbers whose square is the concatenation of two numbers k and k-9.

%e 638370_638361 = 798981^2.

%Y Cf. A030467, A106497, A115436, A115427, A115438, A115439, A115440, A115441, A115442, A115443, A115444, A115445, A115446.

%K base,nonn

%O 1,1

%A _Giovanni Resta_, Jan 25 2006