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 A170837 #27 Sep 08 2022 08:45:49 %S A170837 0,1,5,21,37,53,69,85,101,117,133,149,165,181,197,213,229,245,261,277, %T A170837 293,309,325,341,357,373,389,405,421,437,453,469,485,501,517,533,549, %U A170837 565,581,597,613,629,645,661,677,693,709,725,741,757,773,789,805 %N A170837 a(0)=0, a(1)=1 and a(n) = 16n-27 for n >= 2. %H A170837 Vincenzo Librandi, <a href="/A170837/b170837.txt">Table of n, a(n) for n = 0..1000</a> %H A170837 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1). %F A170837 G.f.: x*(3*x+12*x^2+1)/(x-1)^2. %F A170837 a(n) = 2*a(n-1) -a(n-2), n>=4. %F A170837 a(n) = 4*A016813(n-2) + 1, n>=2. - _Ivan N. Ianakiev_, Jul 20 2013 %t A170837 CoefficientList[Series[x*(3*x + 12*x^2 + 1)/(x - 1)^2, {x, 0, 60}], x] (* _Vincenzo Librandi_, Dec 19 2012 *) %t A170837 LinearRecurrence[{2,-1},{0,1,5,21},60] (* _Harvey P. Dale_, Oct 09 2017 *) %o A170837 (Magma) I:=[0, 1, 5, 21]; [n le 4 select I[n] else 2*Self(n-1) - Self(n-2): n in [1..60]]; // _Vincenzo Librandi_, Dec 19 2012 %Y A170837 Cf. A170836 (first differences), A170876. %K A170837 nonn,easy %O A170837 0,3 %A A170837 _N. J. A. Sloane_, Jan 05 2010, based on email from _R. J. Mathar_ and _Benoit Jubin_, Jun 02 2009; revised Jan 09 2010