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 A023443 #41 Apr 19 2025 04:33:00
%S A023443 -1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,
%T A023443 25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,
%U A023443 48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73
%N A023443 a(n) = n - 1.
%H A023443 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>.
%H A023443 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A023443 From _R. J. Mathar_, Feb 11 2010: (Start)
%F A023443 a(n) = 2*a(n-1) -a(n-2).
%F A023443 G.f.: (-1+2*x)/(1-x)^2. (End)
%F A023443 E.g.f.: exp(x)*(x - 1). - _Stefano Spezia_, Feb 14 2025
%t A023443 Range[0,80]-1 (* _Harvey P. Dale_, Apr 05 2012 *)
%t A023443 LinearRecurrence[{2,-1},{-1,0},75] (* _Ray Chandler_, Jul 30 2015 *)
%o A023443 (PARI) a(n)=n-1 \\ _Charles R Greathouse IV_, Aug 26 2011
%o A023443 (Magma) A023443:= func< n | n-1 >; // _G. C. Greubel_, Apr 18 2025
%o A023443 (Python) def A023443(n): return n-1 # _G. C. Greubel_, Apr 18 2025
%Y A023443 Cf. A000027, A022958-A022996, A023444-A023482, A256958.
%K A023443 sign,easy
%O A023443 0,4
%A A023443 _N. J. A. Sloane_