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A135142 Number of trisubstituted alkanes C_n H_{2n-1} X_2 Y with n carbon atoms. 1
0, 1, 3, 9, 29, 91, 282, 864, 2624, 7905, 23665, 70458, 208813, 616400, 1813354, 5318673, 15559072, 45410239, 132258752, 384493609, 1115907585, 3233782193, 9358293913, 27048189854, 78087437216, 225198736949, 648826102943, 1867669679538, 5371673739750 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
MAPLE
The following Maple commands are taken from the Chyzak web site:
with(combstruct);
gramm_Alkyl:=Alkyl=Prod(Carbon, Set(Alkyl, card<=3)), Carbon=Atom:
specs_Alkyl:=[Alkyl, {gramm_Alkyl}, unlabeled]:
gramm_S1_Alkyl:=S1_Alkyl[X]=Union(Prod(Carbon, S1_Alkyl[X], Set(Alkyl, card<=2)), Prod(Prod(Carbon, X), Set(Alkyl, card<=2))), X=Epsilon:
specs_S1_Alkyl:=[S1_Alkyl[X], {gramm_S1_Alkyl, gramm_Alkyl}, unlabeled]:
gramm_S2b_Alkyl:=S2_Alkyl[X, X]=Union(Prod(Carbon, S2_Alkyl[X, X], Set(Alkyl, card<=2)), Prod(Carbon, Union(Prod(S1_Alkyl[X], S1_Alkyl[X]), Prod(S1_Alkyl[X], X), Prod(X, X)), Set(Alkyl, card<=1))):
specs_S2b_Alkyl:=[S2_Alkyl[X, X], {gramm_S2b_Alkyl, gramm_S1_Alkyl, gramm_Alkyl}, unlabeled]:
[seq(count(specs_S2b_Alkyl, size=i), i=0..50)];
CROSSREFS
Sequence in context: A123947 A262253 A303546 * A195624 A098589 A024744
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 14 2008
STATUS
approved

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Last modified March 29 06:57 EDT 2024. Contains 371265 sequences. (Running on oeis4.)