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 A020346 #24 Dec 17 2024 15:16:13
%S A020346 1,23,359,4747,57351,655683,7229839,77760587,821694071,8571599443,
%T A020346 88563029919,908455411227,9267399149191,94137972490403,
%U A020346 953097676407599,9624750893682667,96997854561570711,975982073553112563
%N A020346 Expansion of 1/((1-5x)(1-8x)(1-10x)).
%H A020346 Vincenzo Librandi, <a href="/A020346/b020346.txt">Table of n, a(n) for n = 0..200</a>
%H A020346 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (23,-170,400).
%F A020346 a(n) = 5^(n+1)/3 -4*8^(n+1)/3+10^(n+1). - _R. J. Mathar_, Mar 15 2011
%F A020346 a(0)=1, a(1)=23, a(2)=359; for n>2, a(n) = 23*a(n-1) -170*a(n-2) +400*a(n-3). - _Vincenzo Librandi_, Jul 03 2013
%F A020346 a(n) = 18*a(n-1) -80*a(n-2) +5^n. - _Vincenzo Librandi_, Jul 03 2013
%t A020346 CoefficientList[Series[1 / ((1 - 5 x) (1 - 8 x) (1 - 10 x)),{x, 0, 20}], x] (* _Vincenzo Librandi_, Jul 03 2013 *)
%o A020346 (PARI) a(n) = 5^(n+1)/3-32*8^n/3+10^(n+1) \\ _Charles R Greathouse IV_, Sep 26 2012
%o A020346 (Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-5*x)*(1-8*x)*(1-10*x)))); // _Vincenzo Librandi_, Jul 03 2013
%o A020346 (Magma) I:=[1, 23, 359]; [n le 3 select I[n] else 23*Self(n-1)-170*Self(n-2)+400*Self(n-3): n in [1..20]]; // _Vincenzo Librandi_, Jul 03 2013
%K A020346 nonn,easy
%O A020346 0,2
%A A020346 _N. J. A. Sloane_