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 A001027 M5062 N2192 #74 Jul 02 2025 16:01:54
%S A001027 1,18,324,5832,104976,1889568,34012224,612220032,11019960576,
%T A001027 198359290368,3570467226624,64268410079232,1156831381426176,
%U A001027 20822964865671168,374813367582081024,6746640616477458432,121439531096594251776,2185911559738696531968,39346408075296537575424,708235345355337676357632,12748236216396078174437376
%N A001027 Powers of 18.
%C A001027 Same as Pisot sequences E(1, 18), L(1, 18), P(1, 18), T(1, 18). Essentially same as Pisot sequences E(18, 324), L(18, 324), P(18, 324), T(18, 324). See A008776 for definitions of Pisot sequences.
%C A001027 The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n>=1, a(n) equals the number of 18-colored compositions of n such that no adjacent parts have the same color. - _Milan Janjic_, Nov 17 2011
%D A001027 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A001027 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A001027 T. D. Noe, <a href="/A001027/b001027.txt">Table of n, a(n) for n = 0..100</a>
%H A001027 P. J. Cameron, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL3/groups.html">Sequences realized by oligomorphic permutation groups</a>, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.
%H A001027 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=282">Encyclopedia of Combinatorial Structures 282</a>
%H A001027 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A001027 Simon Plouffe, <a href="https://arxiv.org/abs/0911.4975">Approximations de séries génératrices et quelques conjectures</a>, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
%H A001027 Simon Plouffe, <a href="/A000051/a000051_2.pdf">1031 Generating Functions</a>, Appendix to Thesis, Montreal, 1992
%H A001027 Y. Puri and T. Ward, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL4/WARD/short.html">Arithmetic and growth of periodic orbits</a>, J. Integer Seqs., Vol. 4 (2001), #01.2.1.
%H A001027 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (18).
%F A001027 G.f.: 1/(1-18x), e.g.f.: exp(18x).
%F A001027 a(n) = 18^n; a(n) = 18*a(n-1) with a(0)=1. - _Vincenzo Librandi_, Nov 21 2010
%p A001027 A001027:=-1/(-1+18*z); # _Simon Plouffe_ in his 1992 dissertation
%t A001027 Table[18^n,{n,0,40}] (* _Vladimir Joseph Stephan Orlovsky_, Feb 15 2011 *)
%o A001027 (Sage) [18**n for n in range(20)] # _F. Chapoton_, Feb 23 2020
%o A001027 (Sage) [lucas_number1(n,18,0) for n in range(1, 17)] # _Zerinvary Lajos_, Apr 29 2009
%o A001027 (Magma) [ 18^n: n in [0..20] ]; // _Vincenzo Librandi_, Nov 21 2010
%o A001027 (PARI) a(n)=18^n \\ _Charles R Greathouse IV_, Sep 28 2015
%K A001027 nonn,easy
%O A001027 0,2
%A A001027 _N. J. A. Sloane_
%E A001027 More terms from _James Sellers_, Sep 19 2000