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 A258132 #10 Oct 19 2017 03:44:25
%S A258132 4715040,8463840,1122749669280,2015496399840,267373851637578960,
%T A258132 479974343542849680,63672943775553479639280,114302050117965712710960,
%U A258132 15163202176330482896520455040,27220118818712616412771202880,3610995292612020914167620625112640
%N A258132 Octagonal numbers (A000567) that are the sum of fifteen consecutive octagonal numbers.
%H A258132 Colin Barker, <a href="/A258132/b258132.txt">Table of n, a(n) for n = 1..370</a>
%H A258132 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,238142,-238142,-1,1).
%F A258132 G.f.: -240*x*(7*x^4 +4*x^3 -449376*x^2 +15620*x +19646)/((x-1)*(x^2 -488*x +1)*(x^2 +488*x +1)).
%e A258132 4715040 is in the sequence because Oct(1254) = 4715040 = 300833 + 302736 + 304645 + 306560 + 308481 + 310408 + 312341 + 314280 + 316225 + 318176 + 320133 + 322096 + 324065 + 326040 + 328021 = Oct(317) + ... + Oct(331).
%t A258132 CoefficientList[Series[-240*x*(7*x^4 +4*x^3 -449376*x^2 +15620*x +19646)/((x-1)*(x^2 -488*x +1)*(x^2 +488*x +1)), {x, 0, 50}], x] (* _G. C. Greubel_, Oct 18 2017 *)
%o A258132 (PARI) Vec(-240*x*(7*x^4 +4*x^3 -449376*x^2 +15620*x +19646)/((x-1)*(x^2 -488*x +1)*(x^2 +488*x +1)) + O('x^20))
%Y A258132 Cf. A000567, A258128, A258129, A258130, A258131.
%K A258132 nonn,easy
%O A258132 1,1
%A A258132 _Colin Barker_, May 21 2015