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 A257708 #8 Jun 13 2015 00:55:36
%S A257708 25,55,208,382,1273,2287,7480,13390,43657,78103,254512,455278,1483465,
%T A257708 2653615,8646328,15466462,50394553,90145207,293721040,525404830,
%U A257708 1711931737,3062283823,9977869432,17848298158,58155284905,104027505175,338953840048,606316732942
%N A257708 Numbers n such that T(n) + T(n+1) + ... + T(n+24) is a square, where T = A000217 (triangular numbers).
%C A257708 Positive integers y in the solutions to 2*x^2-25*y^2-625*y-5200 = 0.
%H A257708 Colin Barker, <a href="/A257708/b257708.txt">Table of n, a(n) for n = 1..1000</a>
%H A257708 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,6,-6,-1,1).
%F A257708 G.f.: x*(x^2+4*x+5)*(2*x^2-2*x-5) / ((x-1)*(x^2-2*x-1)*(x^2+2*x-1)).
%t A257708 LinearRecurrence[{1, 6, -6, -1, 1}, {25, 55, 208, 382, 1273}, 50] (* _Vincenzo Librandi_, May 05 2015 *)
%o A257708 (PARI) Vec(x*(x^2+4*x+5)*(2*x^2-2*x-5)/((x-1)*(x^2-2*x-1)*(x^2+2*x-1)) + O(x^100))
%Y A257708 Cf. A176541, A176542, A000217, A000292, A001110, A077415.
%Y A257708 Cf. A116476 (length 11), A257293 (length 13), A257707 (length 23), A257709 (length 27), A257710 (length 37).
%K A257708 nonn,easy
%O A257708 1,1
%A A257708 _Colin Barker_, May 04 2015