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 A144942 #30 Jun 16 2025 21:38:02
%S A144942 0,25,532,29237,614312,33739857,708915900,38935766125,818088334672,
%T A144942 44931840368777,944073229295972,51851304849802917,1089459688519217400,
%U A144942 59836360864832197825,1257235536477947584012,69051108586711506487517,1450848719635862992732832
%N A144942 Expansion of x^2*(3*x^3+145*x^2-507*x-25) / ((x-1)*(x^2-34*x+1)*(x^2+34*x+1)).
%C A144942 Also the index of the first of two consecutive pentagonal numbers whose sum is also a pentagonal number. - _Colin Barker_, Dec 22 2014
%H A144942 Vincenzo Librandi, <a href="/A144942/b144942.txt">Table of n, a(n) for n = 1..200</a>
%H A144942 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,1154,-1154,-1,1).
%t A144942 CoefficientList[Series[x (3 x^3 + 145 x^2 - 507 x - 25)/((x - 1) (x^2 - 34 x + 1) (x^2 + 34 x + 1)), {x, 0, 20}], x] (* _Vincenzo Librandi_, Oct 20 2014 *)
%t A144942 LinearRecurrence[{1,1154,-1154,-1,1},{0,25,532,29237,614312},20] (* _Harvey P. Dale_, Jun 16 2025 *)
%o A144942 (PARI) concat(0, Vec(x^2*(3*x^3+145*x^2-507*x-25)/((x-1)*(x^2-34*x+1)*(x^2+34*x+1)) + O(x^20))) \\ _Colin Barker_, Oct 20 2014
%Y A144942 Cf. A133301, A144796, A144797.
%K A144942 easy,nonn
%O A144942 1,2
%A A144942 _Richard Choulet_, Sep 26 2008
%E A144942 a(6) corrected, and more terms from _Colin Barker_, Oct 20 2014
%E A144942 Edited, name changed by _Colin Barker_, Oct 20 2014