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%I M1641 #20 Jan 17 2018 11:39:22
%S 0,0,0,0,2,6,20,60,176,510,1484,4314,12624,37126,109864,326958,978528,
%T 2943384,8895792,27001378,82281216,251636434,772101086,2376186784,
%U 7333094178,22688117658,70360646672,218678194238,681016789056
%N Number of chiral planted trees with n nodes.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H R. W. Robinson, F. Harary and A. T. Balaban, <a href="http://dx.doi.org/10.1016/0040-4020(76)80049-X">The numbers of chiral and achiral alkanes and monosubstituted alkanes</a>, Tetrahedron 32 (1976), 355-361.
%H R. W. Robinson, F. Harary and A. T. Balaban, <a href="/A000625/a000625.pdf">Numbers of chiral and achiral alkanes and monosubstituted alkanes</a>, Tetrahedron 32 (3) (1976), 355-361. (Annotated scanned copy)
%H <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a>
%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%F a(n) = A000625(n)-A005627(n) (given as g(n)=s(n)-p(n) on p. 357 of the Robinson et al. paper). - _Emeric Deutsch_, May 16 2004
%p s[0]:=1:s[1]:=1:for n from 0 to 60 do s[n+1/3]:=0 od:for n from 0 to 60 do s[n+2/3]:=0 od:for n from 1 to 55 do s[n+1]:=(2*n/3*s[n/3]+sum(j*s[j]*sum(s[k]*s[n-j-k],k=0..n-j),j=1..n))/n od:p[0]:=1: for n from 0 to 50 do p[n+1]:=sum(s[k]*p[n-2*k],k=0..floor(n/2)) od:seq(s[n]-p[n],n=0..37); # here s[n]=A000625 and p[n]=A005627(n)
%Y Cf. A000625, A005627.
%K nonn
%O 0,5
%A _N. J. A. Sloane_.
%E More terms from _Emeric Deutsch_, May 16 2004
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