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 A064487 #37 Jun 14 2024 22:31:10
%S A064487 20,29120,32537600,34093383680,35115786567680,36011213418659840,
%T A064487 36888985097480437760,37777778976635853209600,
%U A064487 38685331082014736871587840,39614005699412557795646504960,40564799864499450381466515537920
%N A064487 Order of twisted Suzuki group Sz(2^(2*n + 1)), also known as the group 2B2(2^(2*n + 1)).
%C A064487 Every term in A056866 is divisible by 12 or 20. Those terms that are not divisible by 12 are divisible by a term from this sequence. - _Charles R Greathouse IV_ via _Danny Rorabaugh_, Apr 21 2015
%C A064487 For n >= 3, a(n) has at least 5 distinct prime factors. See my link for a proof. - _Jianing Song_, Apr 04 2022
%D A064487 R. W. Carter, Simple Groups of Lie Type, Wiley 1972, Chap. 14.
%D A064487 J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites].
%H A064487 Vincenzo Librandi, <a href="/A064487/b064487.txt">Table of n, a(n) for n = 0..200</a>
%H A064487 J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites], p. xvi. See <a href="http://brauer.maths.qmul.ac.uk/Atlas/v3/">ATLAS v. 3</a>
%H A064487 Jianing Song, <a href="/A064487/a064487.txt">Proof that a(n) has at least 5 distinct prime factors for n >= 3</a>
%H A064487 Michio Suzuki, <a href="http://www.pnas.org/content/46/6/868.full.pdf">A new type of simple groups of finite order</a>, Proc Natl Acad Sci U S A. 46:6 (1960), pp. 868-870.
%H A064487 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1360,-365568,22282240,-268435456).
%F A064487 a(n) = q^4*(q^2-1)*(q^4+1), where q^2 = 2^(2*n+1).
%F A064487 G.f.: 20*(1+128*x)*(1-32*x+16384*x^2) / ((1-16*x)*(1-64*x)*(1-256*x)*(1-1024*x)). - _Colin Barker_, Dec 25 2015
%t A064487 LinearRecurrence[{1360,-365568,22282240,-268435456},{20,29120,32537600,34093383680},20] (* _Harvey P. Dale_, Sep 08 2018 *)
%o A064487 (GAP) g := Sz(32); s := Size(g);
%o A064487 (Magma) [ #Sz(2^(2*n+1)) : n in [0..10]]; // Sergei Haller (sergei(AT)sergei-haller.de), Dec 21 2006
%o A064487 (PARI) a(n)=my(t=2^(2*n+1)); t^2*(t-1)*(t^2+1) \\ _Charles R Greathouse IV_, Apr 21 2015
%o A064487 (PARI) Vec(20*(1+128*x)*(1-32*x+16384*x^2)/((1-16*x)*(1-64*x)*(1-256*x)*(1-1024*x)) + O(x^20)) \\ _Colin Barker_, Dec 25 2015
%Y A064487 Cf. A037250, A064583. A257391 is a subsequence.
%K A064487 nonn,easy
%O A064487 0,1
%A A064487 Dan Fux (dan.fux(AT)OpenGaia.com or danfux(AT)OpenGaia.com), Oct 15 2001