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 A116187 #8 Jul 19 2021 22:37:18 %S A116187 12,43,20440836,30017751,61336887,52400871197755334426147587, %T A116187 53651708763838760619655612,56652002793835820319625612, %U A116187 57952296063256269823192087,17684775866714240650923831481623 %N A116187 Numbers k such that k concatenated with k+4 gives the product of two numbers which differ by 6. %C A116187 Also numbers k such that k concatenated with k+9 gives the product of two numbers which differ by 4. For proof that this is the same sequence compare A116133. %e A116187 61336887//61336891 = 78317867 * 78317873, where // denotes concatenation. 61336887//61336896 = 78317868 * 78317872. %Y A116187 Cf. A116173, A115429, A116133, A116194, A116318. %Y A116187 Cf. A116193, A116180, A116350. %K A116187 nonn,base %O A116187 1,1 %A A116187 _Giovanni Resta_, Feb 06 2006 %E A116187 Edited by _N. J. A. Sloane_, Apr 11 2007