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 A056452 #47 Sep 08 2022 08:45:01
%S A056452 1,6,6,36,36,216,216,1296,1296,7776,7776,46656,46656,279936,279936,
%T A056452 1679616,1679616,10077696,10077696,60466176,60466176,362797056,
%U A056452 362797056,2176782336,2176782336,13060694016,13060694016,78364164096
%N A056452 a(n) = 6^floor((n+1)/2).
%C A056452 Number of achiral rows of length n using up to six different colors. For a(3) = 36, the rows are AAA, ABA, ACA, ADA, AEA, AFA, BAB, BBB, BCB, BDB, BEB, BFB, CAC, CBC, CCC, CDC, CEC, CFC, DAD, DBD, DCD, DDD, DED, DFD, EAE, EBE, ECE, EDE, EEE, EFE, FAF, FBF, FCF, FDF, FEF, and FFF. - _Robert A. Russell_, Nov 08 2018
%C A056452 Also: a(n) is the number of palindromes with n digits using a maximum of six different symbols. - _David A. Corneth_, Nov 09 2018
%D A056452 M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]
%H A056452 Vincenzo Librandi, <a href="/A056452/b056452.txt">Table of n, a(n) for n = 0..2000</a>
%H A056452 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,6).
%F A056452 a(n) = 6^floor((n+1)/2).
%F A056452 a(n) = 6*a(n-2). - _Colin Barker_, May 06 2012
%F A056452 G.f.: (1+6*x) / (1-6*x^2). - _Colin Barker_, May 06 2012 [Adapted to offset 0 by _Robert A. Russell_, Nov 08 2018]
%F A056452 a(n) = C(6,0)*A000007(n) + C(6,1)*A057427(n) + C(6,2)*A056453(n) + C(6,3)*A056454(n) + C(6,4)*A056455(n) + C(6,5)*A056456(n) + C(6,6)*A056457(n). - _Robert A. Russell_, Nov 08 2018
%p A056452 A056452:=n->6^floor((n+1)/2);
%t A056452 Riffle[6^Range[0, 20], 6^Range[20]] (* _Harvey P. Dale_, Jun 18 2017 *)
%t A056452 Table[6^Ceiling[n/2], {n,0,40}] (* or *)
%t A056452 LinearRecurrence[{0, 6}, {1, 6}, 40] (* _Robert A. Russell_, Nov 08 2018 *)
%o A056452 (Magma) [6^Floor((n+1)/2): n in [0..40]]; // _Vincenzo Librandi_, Aug 16 2011
%Y A056452 Column k=6 of A321391.
%Y A056452 Cf. A016116.
%Y A056452 Cf. A000400 (oriented), A056308 (unoriented), A320524 (chiral).
%K A056452 nonn,easy
%O A056452 0,2
%A A056452 _Marks R. Nester_
%E A056452 a(0)=1 prepended by _Robert A. Russell_, Nov 08 2018
%E A056452 Name corrected by _David A. Corneth_, Nov 08 2018