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 A305548 #56 Apr 10 2025 16:34:21 %S A305548 0,27,54,81,108,135,162,189,216,243,270,297,324,351,378,405,432,459, %T A305548 486,513,540,567,594,621,648,675,702,729,756,783,810,837,864,891,918, %U A305548 945,972,999,1026,1053,1080,1107,1134,1161,1188,1215,1242,1269,1296,1323,1350,1377,1404,1431,1458,1485,1512 %N A305548 a(n) = 27*n. %H A305548 Eric Chen, <a href="/A305548/b305548.txt">Table of n, a(n) for n = 0..1000</a> %H A305548 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1). %F A305548 a(n) = 27*n. %F A305548 a(n) = A008585(A008591(n)) = A008591(A008585(n)). %F A305548 G.f.: 27*x/(x-1)^2. %F A305548 From _Elmo R. Oliveira_, Apr 10 2025: (Start) %F A305548 E.g.f.: 27*x*exp(x). %F A305548 a(n) = 2*a(n-1) - a(n-2). (End) %t A305548 Range[0,2000,27] %o A305548 (PARI) a(n)=27*n %Y A305548 For a(n) = k*n: A001489 (k=-1), A000004 (k=0), A001477 (k=1), A005843 (k=2), A008585 (k=3), A008591 (k=9), A008607 (k=25), A252994 (k=26), this sequence (k=27), A135628 (k=28), A195819 (k=29), A249674 (k=30), A135631 (k=31), A174312 (k=32), A044102 (k=36), A085959 (k=37), A169823 (k=60), A152691 (k=64). %K A305548 nonn,easy %O A305548 0,2 %A A305548 _Eric Chen_, Jun 05 2018