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 A140787 #31 Sep 08 2022 08:45:34
%S A140787 1,1,7,9,39,57,199,313,967,1593,4551,7737,20935,36409,94663,167481,
%T A140787 422343,757305,1864135,3378745,8155591,14913081,35418567,65244729,
%U A140787 152859079,283348537,656175559,1222872633,2803659207,5249404473
%N A140787 Expansion of 1 / ( (1+x)*(2*x+1)*(-1+2*x)^2 ).
%H A140787 Vincenzo Librandi, <a href="/A140787/b140787.txt">Table of n, a(n) for n = 0..1000</a>
%H A140787 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,6,-4,-8).
%F A140787 a(n) = 2^n*(n/3 + 11/18) + (-1)^n* (2^(n-1) - 1/9).
%F A140787 a(2n) - 2a(2n-1) = A002450(n+1).
%F A140787 a(n) + a(n+1) = A134353(n+1). - _R. J. Mathar_, Nov 10 2013
%t A140787 max = 40; j[n_] := (2^n-(-1)^n)/3; jj = Table[{j[n], -j[n]}, {n, 0, max+2, 2}] // Flatten; a[0] = 1; a[n_] := a[n] = 2*a[n-1] + jj[[n+3]]; Table[a[n], {n, 0, max}] (* _Jean-François Alcover_, Sep 30 2013 *)
%o A140787 (Magma) [2^n*(n/3+11/18) + (-1)^n* (2^(n-1)-1/9): n in [0..40]]; // _Vincenzo Librandi_, Aug 08 2011
%Y A140787 Cf. A092808, A094359, A140505.
%K A140787 nonn,easy
%O A140787 0,3
%A A140787 _Paul Curtz_, Jul 14 2008
%E A140787 Better name from _R. J. Mathar_, Jul 02 2011
%E A140787 Edited by _Ralf Stephan_, Nov 10 2013