%N Numbers k such that the concatenation of k with k+9 gives a square.
%C Also numbers k such that k concatenated with k+8 gives the product of two numbers which differ by 2.
%C Also numbers k such that k concatenated with k+5 gives the product of two numbers which differ by 4.
%e 82640_82649 = 90907^2.
%Y Cf. A030465, A102567, A115426, A115437, A115428, A115429, A115431, A115432, A115433, A115434, A115435, A115436, A115441.
%Y Cf. A116172, A116168, A116344, A116112, A116193, A116173, A116323.
%A _Giovanni Resta_, Jan 24 2006
%E Edited by _N. J. A. Sloane_, Apr 13 2007