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 A156199 #20 Feb 25 2024 05:59:05
%S A156199 1,1,4,2,4,1,1,2,7,1,7,2,1,1,4,2,4,1,1,2,7,1,7,2,1,1,4,2,4,1,1,2,7,1,
%T A156199 7,2,1,1,4,2,4,1,1,2,7,1,7,2,1,1,4,2,4,1,1,2,7,1,7,2,1,1,4,2,4,1,1,2,
%U A156199 7,1,7,2,1,1,4,2,4,1,1,2,7,1,7,2,1,1,4,2,4,1,1,2,7,1,7,2,1,1,4,2,4,1,1,2,7
%N A156199 Period 12: repeat 1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2 .
%C A156199 The period is essentially the reversal of the period in A156194.
%C A156199 The first 7 elements of the period (1, 1, 4, 2, 4, 1, 1) are palindromic and the other 5, (2, 7, 1, 7, 2), too.
%H A156199 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,0,0,0,1).
%F A156199 a(n) = A156094(n) mod 9.
%F A156199 a(n) = A156194(n+6).
%F A156199 G.f.: (1 + x + 4*x^2 + 2*x^3 + 4*x^4 + x^5 + x^6 + 2*x^7 + 7*x^8 + x^9 + 7*x^10 + 2*x^11)/( (1-x) * (1+x+x^2) * (1+x) * (1-x+x^2) * (1+x^2) * (x^4-x^2+1)). - _R. J. Mathar_, Nov 22 2009
%t A156199 LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},{1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2},105] (* _Ray Chandler_, Aug 08 2015 *)
%t A156199 PadRight[{},110,{1,1,4,2,4,1,1,2,7,1,7,2}] (* _Harvey P. Dale_, Sep 14 2020 *)
%Y A156199 Cf. A156194.
%K A156199 nonn,easy,less
%O A156199 0,3
%A A156199 _Paul Curtz_, Feb 05 2009
%E A156199 Edited by _R. J. Mathar_, Nov 22 2009