%I A025168
%S A025168 1,1,5,37,361,4361,62701,1044205,19748177,417787921,9770678101,250194150581,
%T A025168 6959638411705,208919770666777,6729933476435261,231512615111396221,8469125401589550241,
%U A025168 328241040596380393505,13434223364220816489637,578931271898150002093381
%N A025168 E.g.f.: exp(x/(1-2*x)).
%H A025168 K. A. Penson, P. Blasiak, G. Duchamp, A. Horzela and A. I. Solomon, <a 
               href="http://arXiv.org/abs/quant-ph/0312202">Hierarchical Dobinski-type 
               relations via substitution and the moment problem</a> [J. Phys. A 
               37 (2004), 3475-3487]
%H A025168 N. J. A. Sloane, <a href="transforms.txt">Transforms</a>
%H A025168 N. J. A. Sloane and Thomas Wieder, <a href="http://arXiv.org/abs/math.CO/
               0307064">The Number of Hierarchical Orderings</a>, Order 21 (2004), 
               83-89.
%H A025168 Thomas Wieder, <a href="a103446.txt">Expanded definitions of A103446 
               and A025168</a>
%F A025168 Second LAH transform of A000012. LAH transform of A000262. a(n) = Sum_{k=0..n) 
               2^(n-k)*n!/k!*binomial(n-1, k-1). - Vladeta Jovovic (vladeta(AT)eunet.rs), 
               Oct 17 2003
%F A025168 Define f_1(x),f_2(x),... such that f_1(x)=e^x, f_{n+1}(x)=diff(x^2*f_n(x),
               x), for n=2,3,.... Then a(n)=e^{-1/2}*4*{n-1}*f_n(1/2). - Milan R. 
               Janjic (agnus(AT)blic.net), May 30 2008
%p A025168 with(combstruct); SetSeqSeqL := [T, {T=Set(S), S=Sequence(U,card >= 1), 
               U=Sequence(Z,card >=1)},labeled];
%t A025168 Table[ n! 2^n LaguerreL[ n, 1, -1/2 ], {n, 0, 12} ]
%Y A025168 Cf. A103446.
%Y A025168 Sequence in context: A084212 A004208 A112698 this_sequence A084358 A050351 
               A129137
%Y A025168 Adjacent sequences: A025165 A025166 A025167 this_sequence A025169 A025170 
               A025171
%K A025168 nonn
%O A025168 0,3
%A A025168 w.meeussen (wouter.meeussen(AT)pandora.be)
%E A025168 Corrected and extended by Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 
               08 2002