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%I M1293 #39 Nov 17 2022 07:21:04
%S 1,1,2,4,16,56,256,1072,11264,78976,672256,4653056,49810432,433429504,
%T 4448608256,39221579776,1914926104576,29475151020032,501759779405824,
%U 6238907914387456,120652091860975616,1751735807564578816,29062253310781161472,398033706586943258624
%N Number of degree-n permutations of order a power of 2.
%C Differs from A053503 first at n=32. - _Alois P. Heinz_, Feb 14 2013
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%D R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.2.10.
%H Alois P. Heinz, <a href="/A005388/b005388.txt">Table of n, a(n) for n = 0..200</a>
%H J. M. Møller, <a href="http://arxiv.org/abs/1502.01317">Euler characteristics of equivariant subcategories</a>, arXiv preprint arXiv:1502.01317, 2015. See page 20.
%H L. Moser and M. Wyman, <a href="http://dx.doi.org/10.4153/CJM-1955-020-0">On solutions of x^d = 1 in symmetric groups</a>, Canad. J. Math., 7 (1955), 159-168.
%H A. Recski, <a href="/A005387/a005387_1.pdf">Enumerating partitional matroids</a>, Preprint.
%H A. Recski & N. J. A. Sloane, <a href="/A005387/a005387.pdf">Correspondence, 1975</a>
%F E.g.f.: exp(Sum(x^(2^m)/2^m, m >=0)).
%p a:= proc(n) option remember; `if`(n<0, 0, `if`(n=0, 1,
%p add(mul(n-i, i=1..2^j-1)*a(n-2^j), j=0..ilog2(n))))
%p end:
%p seq(a(n), n=0..25); # _Alois P. Heinz_, Feb 14 2013
%t max = 23; CoefficientList[ Series[ Exp[ Sum[x^2^m/2^m, {m, 0, max}]], {x, 0, max}], x]*Range[0, max]! (* _Jean-François Alcover_, Sep 10 2013 *)
%o (Magma)
%o R<x>:=PowerSeriesRing(Rationals(), 40);
%o f:= func< x | Exp( (&+[x^(2^j)/2^j: j in [0..14]]) ) >;
%o Coefficients(R!(Laplace( f(x) ))); // _G. C. Greubel_, Nov 17 2022
%o (SageMath)
%o def f(x): return exp(sum(x^(2^j)/2^j for j in range(15)))
%o def A005388_list(prec):
%o P.<x> = PowerSeriesRing(QQ, prec)
%o return P( f(x) ).egf_to_ogf().list()
%o A005388_list(40) # _G. C. Greubel_, Nov 17 2022
%Y Cf. A000085, A001470, A001472, A053495, A053496, A053497, A053498, A053499.
%Y Cf. A053500, A053501, A053502, A053503, A053504, A053505.
%K nonn,nice,easy
%O 0,3
%A _N. J. A. Sloane_ and _J. H. Conway_
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