A115430 - OEIS

%I #8 Jul 15 2021 06:20:15

%S 216,287,515,675,1175,4320,82640,960795,1322312,4049591,16955015,

%T 34602080,171010235,181964891,183673467,187160072,321920055,326530616,

%U 328818032,343942560,470954312,526023432,528925616,534830855

%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.

%K base,nonn

%O 1,1

%A _Giovanni Resta_, Jan 24 2006

%E Edited by _N. J. A. Sloane_, Apr 13 2007