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 A131757 #11 Dec 12 2023 09:25:43
%S A131757 3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,
%T A131757 3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,
%U A131757 3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,3,3,3,-7,3,3,-7,3,3,-7,3
%N A131757 Period 10: repeat 3, 3, 3, -7, 3, 3, -7, 3, 3, -7.
%H A131757 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,-1,-1,-1,-1,-1,-1,-1).
%t A131757 PadRight[{},120,{3,3,3,-7,3,3,-7,3,3,-7}] (* _Harvey P. Dale_, Aug 07 2018 *)
%o A131757 (PARI) a(n)=[3, 3, 3, -7, 3, 3, -7, 3, 3, -7][n%10+1] \\ _Charles R Greathouse IV_, Jul 13 2016
%Y A131757 Cf. A010705, A096915.
%K A131757 sign,easy
%O A131757 0,1
%A A131757 _Paul Curtz_, Oct 04 2007