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 A142888 #19 Apr 02 2018 15:50:50
%S A142888 3,-1,13,-9,29,-23,51,-43,79,-69,113,-101,153,-139,199,-183,251,-233,
%T A142888 309,-289,373,-351,443,-419,519,-493,601,-573,689,-659,783,-751,883,
%U A142888 -849,989,-953,1101,-1063,1219,-1179,1343,-1301,1473,-1429,1609,-1563,1751
%N A142888 First differences of A142705.
%C A142888 Also obtained from A135370 if adjacent pairs are swapped and if the sequence is then multiplied by (-1)^(n+1).
%H A142888 Vincenzo Librandi, <a href="/A142888/b142888.txt">Table of n, a(n) for n = 1..1000</a>
%H A142888 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (-1,2,2,-1,-1).
%F A142888 a(n) = A142705(n+1)-A142705(n).
%F A142888 a(n) = -a(n-1) +2*a(n-2) +2*a(n-3) -a(n-4) -a(n-5). - _R. J. Mathar_, Sep 12 2010
%F A142888 a(2n-1)+a(2n) = A005843(n).
%F A142888 G.f.: x(3+2x+6x^2-x^4)/((1+x)^3*(1-x)^2). - _R. J. Mathar_, Oct 24 2008, parenthesis added Sep 12 2010
%F A142888 From _Colin Barker_, Jan 26 2016: (Start)
%F A142888 a(n) = (5+3*(-1)^n+(10-6*(-1)^n)*n-6*(-1)^n*n^2)/8.
%F A142888 a(n) = (-3*n^2+2*n+4)/4 for n even.
%F A142888 a(n) = (3*n^2+8*n+1)/4 for n odd.
%F A142888 (End)
%t A142888 CoefficientList[Series[(3 + 2 x + 6 x^2 - x^4)/((1 + x)^3 (1 - x)^2), {x, 0, 60}], x] (* _Vincenzo Librandi_, May 25 2014 *)
%t A142888 LinearRecurrence[{-1,2,2,-1,-1},{3,-1,13,-9,29},50] (* _Harvey P. Dale_, Apr 02 2018 *)
%o A142888 (PARI) Vec(x*(3+2*x+6*x^2-x^4)/((1+x)^3*(1-x)^2) + O(x^100)) \\ _Colin Barker_, Jan 26 2016
%Y A142888 Cf. A005843, A142705.
%K A142888 sign,easy
%O A142888 1,1
%A A142888 _Paul Curtz_, Sep 29 2008
%E A142888 Edited by _R. J. Mathar_, Oct 24 2008
%E A142888 More terms from _Vincenzo Librandi_, May 25 2014