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 A156346 #21 May 27 2024 02:40:51
%S A156346 1,2,-4,4,-2,-1,-1,-2,4,-4,2,1,1,2,-4,4,-2,-1,-1,-2,4,-4,2,1,1,2,-4,4,
%T A156346 -2,-1,-1,-2,4,-4,2,1,1,2,-4,4,-2,-1,-1,-2,4,-4,2,1
%N A156346 Palindromic period of length 12: repeat 1,2,-4,4,-2,-1,-1,-2,4,-4,2,1.
%H A156346 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,-1)
%F A156346 a(n) == A154811(n) (mod 9).
%F A156346 a(n) = ( (2*A154811(n)) mod 9 ) - A154811(n).
%F A156346 G.f.: -(x-1)*(x^4+3*x^3-x^2+3*x+1) / ( (1+x^2)*(x^4-x^2+1) ). - _R. J. Mathar_, Mar 08 2011
%t A156346 PadRight[{},50,{1,2,-4,4,-2,-1,-1,-2,4,-4,2,1}] (* _Harvey P. Dale_, May 29 2021 *)
%Y A156346 Cf. A156283.
%K A156346 easy,sign
%O A156346 0,2
%A A156346 _Paul Curtz_, Feb 08 2009