%I #8 Jul 20 2021 23:46:40
%S 9,49,1166975893986638437392162264780939,
%T 1411174268292962563778302427727571,1860631503683565562655236868895135
%N Numbers k such that k concatenated with k+1 gives the product of two numbers which differ by 9.
%C Also numbers k such that k concatenated with k+9 gives the product of two numbers which differ by 7.
%e 49//50 = 66 * 75, where // denotes concatenation.
%e 49//58 = 67 * 74.
%Y Cf. A116162, A116168, A116175, A116300.
%Y Cf. A116215, A116174, A116223, A116353.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, Feb 06 2006
%E Edited by _N. J. A. Sloane_, Apr 15 2007
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