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 A168615 #19 Jul 21 2024 13:22:14
%S A168615 1,2,-2,0,6,-18,36,-54,54,0,-162,486,-972,1458,-1458,0,4374,-13122,
%T A168615 26244,-39366,39366,0,-118098,354294,-708588,1062882,-1062882,0,
%U A168615 3188646,-9565938,19131876,-28697814,28697814,0,-86093442,258280326,-516560652
%N A168615 Inverse binomial transform of A169609, or of A144437 preceded by 1.
%H A168615 G. C. Greubel, <a href="/A168615/b168615.txt">Table of n, a(n) for n = 0..1000</a>
%H A168615 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (-3,-3).
%F A168615 a(n) = -3*a(n-1) - 3*a(n-2) for n > 2; a(0) = 1, a(1) = 2, a(2) = -2.
%F A168615 a(n) = 2*A123877(n-1), n>0.
%F A168615 G.f.: 1+2*x*(1+2*x)/(1+3*x+3*x^2).
%F A168615 a(6*m + 3) = 0, m>=0. - _G. C. Greubel_, Jul 27 2016
%t A168615 Join[{1,2,-2}, LinearRecurrence[{-3, -3}, {0, 6}, 25]] (* _G. C. Greubel_, Jul 27 2016 *)
%t A168615 LinearRecurrence[{-3,-3},{1,2,-2},40] (* _Harvey P. Dale_, Jul 21 2024 *)
%o A168615 (Magma) [ n le 2 select n else n eq 3 select -2 else -3*Self(n-1)-3*Self(n-2): n in [1..37] ]; // _Klaus Brockhaus_, Dec 03 2009
%Y A168615 Cf. A169609, A144437, A000748, A057083, A057682.
%K A168615 sign
%O A168615 0,2
%A A168615 _Paul Curtz_, Dec 01 2009
%E A168615 Edited and extended by _Klaus Brockhaus_, Dec 03 2009