This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A115430 #8 Jul 15 2021 06:20:15 %S A115430 216,287,515,675,1175,4320,82640,960795,1322312,4049591,16955015, %T A115430 34602080,171010235,181964891,183673467,187160072,321920055,326530616, %U A115430 328818032,343942560,470954312,526023432,528925616,534830855 %N A115430 Numbers k such that the concatenation of k with k+9 gives a square. %C A115430 Also numbers k such that k concatenated with k+8 gives the product of two numbers which differ by 2. %C A115430 Also numbers k such that k concatenated with k+5 gives the product of two numbers which differ by 4. %e A115430 82640_82649 = 90907^2. %Y A115430 Cf. A030465, A102567, A115426, A115437, A115428, A115429, A115431, A115432, A115433, A115434, A115435, A115436, A115441. %Y A115430 Cf. A116172, A116168, A116344, A116112, A116193, A116173, A116323. %K A115430 base,nonn %O A115430 1,1 %A A115430 _Giovanni Resta_, Jan 24 2006 %E A115430 Edited by _N. J. A. Sloane_, Apr 13 2007