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 A116295 #14 Jul 18 2021 02:55:49 %S A116295 8873,9010,83352841,99000100,329767122287,670232877712,738226276372, %T A116295 933006600340,999000001000,3779410975143114,3872816717528066, %U A116295 4250291784692549,4278630943941866,4372036686326818,4749511753491301 %N A116295 Numbers k such that k*(k+2) gives the concatenation of two numbers m and m+1. %C A116295 From _Robert Israel_, Jun 06 2018: (Start) %C A116295 Numbers k such that 10^m+1 | (k+1)^2-2 where (k+1)^2 has 2*m digits. %C A116295 Includes 10^i - 10^(3*i) + 10^(4*i) for all i >= 1. (End) %H A116295 Robert Israel, <a href="/A116295/b116295.txt">Table of n, a(n) for n = 1..600</a> %e A116295 99000100 * 99000102 = 98010199//98010200, where // denotes concatenation. %p A116295 Res:= NULL: %p A116295 for d from 1 to 40 do %p A116295 Res:= Res, op(sort(select(t -> t^2 >= 10^(2*d-1),map(t -> rhs(op(t))-1,[msolve(x^2=2, 10^d+1)])))) %p A116295 od: %p A116295 Res; # _Robert Israel_, Jun 06 2018 %Y A116295 Cf. A115426, A116286, A116294, A116296, A116308. %K A116295 nonn,base %O A116295 1,1 %A A116295 _Giovanni Resta_, Feb 06 2006