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Numbers k such that k concatenated with itself gives the product of two numbers which differ by 9.
4

%I #6 Jul 20 2021 23:46:19

%S 2,92,180,332,486,536,992,9720,9992,13220,40502,99992,941486,999992,

%T 2066120,2975202,9999992,77854680,99999992,123250136,162423540,

%U 243964010,256109750,356387462,421110162,542936282,547361900

%N Numbers k such that k concatenated with itself gives the product of two numbers which differ by 9.

%Y Cf. A116153, A116161, A116169, A116293.

%K nonn,base

%O 1,1

%A _Giovanni Resta_, Feb 06 2006