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 A060170 #16 Jan 05 2025 19:51:36
%S A060170 3,6,27,120,600,3078,16611,91872,520749,3004200,17594247,104304888,
%T A060170 624801957,3775722342,22991161500,140928011136,868886416866,
%U A060170 5384796881850,33525472069563,209592223788000,1315211209630794,8281053081282894,52301607644921259,331260902534858976,2103541885645955625,13389670112374830378
%N A060170 Number of orbits of length n under the map whose periodic points are counted by A005809.
%C A060170 The sequence A005809 records the number of points of period n under a map. The number of orbits of length n for this map gives the sequence above.
%C A060170 a(n) is divisible by n (cf. A268617), 2*a(n) is divisible by n^2 (cf. A268618).
%H A060170 Y. Puri and T. Ward, <a href="http://www.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 A060170 Yash Puri and Thomas Ward, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/39-5/puri.pdf">A dynamical property unique to the Lucas sequence</a>, Fibonacci Quarterly, Volume 39, Number 5 (November 2001), pp. 398-402.
%F A060170 a(n) = (1/n)* Sum_{d|n} A008683(n/d)*A005809(d).
%e A060170 a(3) = 27 since a map whose periodic points are counted by A005809 has 3 fixed points and 84 points of period 3, hence 27 orbits of length 3.
%o A060170 (PARI) a(n) = sumdiv(n, d, moebius(n/d)*binomial(3*d, d))/n; \\ _Michel Marcus_, Sep 10 2017
%Y A060170 Cf. A005809, A060164, A060165, A060166, A060167, A060168, A060179, A060171, A060171, A060172, A060173.
%K A060170 easy,nonn
%O A060170 1,1
%A A060170 _Thomas Ward_, Mar 13 2001
%E A060170 Edited by _Max Alekseyev_, Feb 09 2016